Just a note:

Several years ago, there was a short discussion thread about a program that was used for "kinesiology" (Study of movement) in sports, particularly in training.

The program was free. But, it wouldn't be interesting, except for this little bit - It could import a video file and then create a BVH file from it.

I tried talking the developer into porting it over for use in 3D animation, but no luck. (Needed some extra capabilities, IIRC.) But, from what I saw and read of it, it could have been used for animating any Poser character, given that you have a BVH file editor. (There are several free ones out there, mostly used by the Second Life fans.)

I have the proggy archived, somewhere, but never messed with it. But, it'd be perfect for your project.

Also, there are "pay" programs that will render out BVH files from video feeds, without the need for a motion-capture studio. Yes, they'll probably require a bit of tweaking and, perhaps, some camera tracking stuff. But, if it saves you a lot of time, that's money! :D The workflow shoudl be relatively simple, I'd imagine. (ie: Load the vid and place your markers, name your bones, tweak as necessary, export motion-captured-animation. :D )