Technically it's easy, but you have to keep the restrictions of both media combined in mind ( video is a 2D format, even the stereoscopic variant ). On the other hand, live-action techniques such as motion-capture and 3D-scanning are common ground these days .. they're not exactly cheap though.
Some blasts from the past using digitized actors:
Time Traveler ( 1991 )
Mortal Kombat 3 ( 1995 )
Rise of the Triad ( 1995 )