Monologues are not the ideal thing for a showreel, but if you are planning to organise and shoot it yourself they're probably the best thing to start with.
The reason agents are interested in seeing showreels are that they are a quick way of judging screen acting ability and assessing the sort of role you could be suitable for - that's one aspect of it. The other reason is possibly more important though - it's to show what you have been cast in. It is proof of your employability. That's why broadcast work has more validity than self-shot work on a showreel.
Shot from scratch showreels can be a good way to get yourself cast in student films (which then provide you with more material). If you aim for graduate year films (some of which are paid work btw) then you can get some really good material. For this kind of casting, a self-made showreel may be all you need - and a monologue could be plenty.
Shot from scratch showreels are very, very hard to do well. The best ones look as though they come from genuine short films etc. In many cases, it is the material and lack of knowledgeable direction for the actors that let them down, rather than any technical shortcomings. I have watched some absolute shockers that people have paid a lot of money for.
Monologues are very rare beasts on screen. Screen acting is as much (if not more) about reacting than acting. We learn so much about a character from watching their thoughts and reactions - we also learn how skilled and interesting an actor they are through this. If you have a "scene" for more than one person that is properly written by someone who understands screenwriting then you are much more likely to be able to showcase your screen acting skills.
Choosing material for your showreel:
I usually recommend completely original material, written by someone who understands screenwriting . Writing for screen is a very different thing from writing for stage. Some theatre material comes across well on screen - a lot of it doesn't. For monologues, reflective pieces tend to come across well - where we see the actor reacting to their own thoughts and memories. The vital thing is to choose something really appropriate for your age and accent. The agent will want to see you in the sort of role you could conceivably be cast in - they don't want to see you do Lady Macbeth or Blanche Dubois.
There's a bit more about choosing material in the information below.
If you are going to shoot a monologue, here are some thoughts I offered to someone else on the subject of self tapes - you might find some of it relevant to you:
Setting up the “shoot”:
Practical considerations:
Lighting and sound are really, really important. If someone can’t see and hear you well, it won’t matter how good the acting is. Natural light is probably best, unless you have decent lighting equipment. A large window is usually fine with the light coming from behind or to the side of the camera (even better if it’s both). You need to be able to see the actor’s face - and particularly their eyes - easily/clearly.
Make sure the framing is tight enough and at the right height. You may need to balance the ipad on a pile of books on a table )use a tripod if appropriate for your camera). I would suggest that the actor should be seated, preferably in front of a plain wall with as few distractions for the viewer as possible. A neutral background is what you should be aiming for. If you are struggling to find somewhere suitable, you might find that hanging up a sheet over a bookcase will work : I’m sure you’ll think of something. (Note re: showreel material, you may decide to film the monologue in a place that adds to the speech - but take care that the setting isn't more interesting than the actor!)
The frame should be a medium close up, to mid chest level (or even closer if it looks better that way, it may depend on the speech) – always landscape rather than portrait. Think of a reasonable close up of an actor on TV, one where you can see their eyes clearly – that’s what you should be aiming for. Don’t make the frame so tight that the actor disappears out of the frame with the slightest movement, you need a bit of “air” around them, but generally a tightish frame will give the actor the best chance to impress. It's all in the eyes
Some people shoot outside, which provides great light but can cause sound issues.
The sound/microphone on the ipad should be fine for a self tape, providing you are close enough to the actor and there’s no background noise. A separate mic is ideal, so that you can pick up the actor rather than the surrounding noises.
Choosing the material:
It ideally needs to be in the modern idiom and conversational in style. It needs to be entirely suitable for your age and accent, so choose something that really seems “you”.
Well-written material is of course the easiest to deliver, but for a self tape to work it doesn’t need to be great literature. For a self tape/screen monologue we will be watching thought processes as much as listening to the words.
If you’re struggling to find something suitable then consider adapting a bit from a children’s novel. Sometimes the “narrator” is a young person and there might be passages you could work in to a monologue.
Silence and pauses for (the character’s) thoughts are fascinating to watch, so the piece itself does not have to be long. Definitely err on the side of brevity. I’d suggest two minutes at the very most (you may have been asked for a different length, in which case obviously do that!). One minute would be plenty for most people to make a judgement about an actor. Many people watching showreels in a professional capacity only watch about 30 seconds.
Delivery:
It needs to appear “truthful”. It’s a word much bandied about by actors and directors, but that is, ultimately, what a caster is looking for.
Most young people don’t fall in to the trap that lots of adult amateurs do when approaching screen acting for the first time, which is to speak too slowly and deliberately. The speed of delivery should be conversational – and suitable for the piece and the character. It doesn’t need to be projected at all. The actor just needs to use the volume/tone and speed that they would use in “real life” for this piece. That can feel really odd if you're used to theatre, though some people “get it” straight away.
The actor doesn’t need to “show” what she is thinking. She should never try to “make” us feel anything. That’s one of the brilliant things about the camera: it picks up your thoughts. Unfortunately it also picks up when you’re struggling for lines or not really “living” it – you can’t hide, so you just have to “be”. Sounds a bit arty farty, but it’s one of important things to discover.
A monologue to camera is actually really, really unusual on screen – so it’s quite an artificial thing to do. Most self-tapes will be conversations, with just one side of it being filmed – but both sides recorded.
The actor can choose either to deliver the speech straight to camera – which will look like a video diary – or the speech might be better delivered looking *just* off camera to the left or right of the lens, as if addressing someone we can’t see. It probably depends on the speech.
It’s best to keep the eye line up for most of the speech, though if it feels natural to look away, that’s fine too. You don’t have to look just in one direction (we don’t normally in real life) but if you’re looking elsewhere it’s a good trick to keep your eyes up while you’re thinking rather than down.
A lot of screen acting is about reacting rather than acting and it can be difficult to include this in a monologue. One of the ways you can do this is to give yourself time to react to your own thoughts as they occur to you, or imagining what effect your words are having on the person you are speaking to. That might be one job too many for a first go at screen monologues though… Mostly, it’s just be “truthful”.
Movement:
The actor will need an idea of the frame so that she knows how much she can move within it. She shouldn’t feel trapped by it, but limiting body movement for a self tape is probably a good idea. That doesn’t mean being frozen to the spot!
Ident or slate
This is simply the actor saying (as the actor) “Hello, I’m xxxxxxx this is a piece from….” or words to that effect. This comes before the monologue or self-tape. You can, if you prefer and you have the technology, just put the name and piece as a piece of text on the screen.
Sending the finished product:
The agent or CD will almost certainly tell you how they want to receive it.
If they don’t, I’d suggest a private youtube or vimeo link. That way you just send them the link to the piece hosted on youtube or vimeo rather than sending them a huge file. Make sure you give the file/video a title that will be useful to the person viewing it - mostly, it needs the actor's NAME (and the part they're reading for if applicable). I've lost count of the number I've seen that just say "screen monologue" or "self-tape"...
I hope some of this is helpful. Do let me know if you have any further questions. Best of luck.