Some movie players for linux can be used with OpenGL so it should be easy to check the speed. OpenGL is probably not the fastest alternative. Here is a page if you are looking for a player http://www.mplayerhq.hu/homepage/
If you know hot to get the camera image should it be easy to use them as textures in the same way as in the NeHe tutorial. I think that he used some asm but you can set the color format parameter instead. Xlib graphics can also be mixed with OpenGL.