Hello,
Having tried your patch with Diablo 2, the movies do not show like you say. I don't know if it radeon related. They work without applying your patch though.
Yeah, that is related to the rendertarget locking code. There are some troubles with that in WineD3D, and the current ddraw code does that much better. I have done some tests with a pure gl app, it looks like it's some bug in wine, and not in the driver.
Stefan