I’ve made a Bink Video (http://www.radgametools.com/bnkmain.htm) wrapper for C# and Paradox, which supports rendering to textures. You can literally pass any texture to it, so you could use it on materials, or as full screen video using an ImageElement. Sound is supported as well of course. Would there be any demand for the library? If so, I could tidy it up and release it!
(I’m not quite sure if it’s 100% legal though…)