How to animate a rig by using a video as a source? I have a series of movements that I want to animate, I have videos of the front and side of these movements and would like to know how to setup Blender to use the footage to create the animations.

I have looked at mocap but the cost is a problem and some of the motions have some subtle details that need to be replicated exactly.
In the 3D viewport, you can add background images to use as reference while modelling or animating. You can also add an image to an empty to get an image floating in the viewport that is always visible as you move around. An image sequence or movie can be used as well as a static image.