Not a website, but maybe something you could borrow through an interlibrary loan (if not available at your own):
"Manipulation in Motion: A Video Companion to A Pocket Manual of OMT"
Chicago's DO school used to have a DVD with OMM on it, I'm not sure if they still do. Someone who went to that school sent me the DVD (I don't still have it). If you know anyone who goes to school there, perhaps they could burn a copy for you.