Digital video is a very literal format, so positioning the actors in your scenes needs special care.
A Crafted World
Film as a visual medium requires the action to take place on a simulated world stage only viewable through the screen. Within that small area you need to position the actors realistically, in interaction between each other and their environment, and so all of these things communicate story and emotional elements to the audience. The way that the actors are arranged for each shot in each scene is taken from the theater world, and is called blocking.
When you are thinking about blocking for digital video you have to keep in mind both that you control what is on the screen and you have to keep activity within the constraints of that screen. You have the ability to manipulate a place with camera angles and cut-shots making it look the way you want. Blocking is part of this, and therefore you should decide how you want the environment to look. If you want it to look large have the actors take a longer time to move across the space, and to shrink it have them make larger strides. The most important part of this is to always keep them in frame. The best way to do this is to use markers in the set where the actors know they are supposed to be or move to. This is called hitting your mark. To do this the actors tend to not have as elaborate or practical body movements as they do in real life, especially if it is an extremely tight frame. Their movements are meant to be seen, so anything significant must be tilted at least slightly in the direction of the camera. Depending on the type of themes you are working with, such as working with a more understated performance or a more expressive and theatrical one, you want to alter the movements of the actor.
The best way to arrange the blocking is by working with the actors ahead of time in rehearsals. Here you will communicate what you want as the director and producer and they will attempt to interpret these requests and give feedback. Together you agree on the movements of the characters according to the development they have just taken. From here you can alter the storyboards slightly, but since the images on it are fairly broad and just express basic angles and perspectives you should be able to just discuss it with the director of photography.
The blocking should keep in mind the two-dimensional nature of the medium by trying to integrate visual techniques like the rule of thirds and the Z-axis. Try having them walk to and from the camera at a diagonal angle, and when they are positioned for close-ups try and have there mark be where their eyes meet the top line of thirds on the Y-axis. Do not let the actors remain static in their position, even if this would be their natural state. Have them move around and be somewhat expressive because this is the best way to maintain visual energy.
When blocking out a scene you must keep in mind the intent of the sequence and make sure the movements of the actors will maximize every angle for its content. Do not let your vision overwhelm the reality of the shooting situation and always be open to advice and suggestions from the cast and crew.