OpenGL movies

Hi, its been some time since posting on this board, but a new project needs video (various formats) to be decoded and then used/analysed/superimposed using opengl. What is the best route to take? The simpler the better, in terms of end user understanding of code and cross platform usage. Ideally a nice C lib for decoding would be nice. The easier the decoding (for all of the users) the better, and then just accessed for the rest of the work.

Thanks for any help