I just recently shot a music video on a Canon with (mostly) a Nikon 50mm f/1.4.
I have three reasons for this:
1. The lens was a bargain (used), $100.
2. Full manual control.
3. I love the way it looks. The video quality, I mean, not the lens on the camera.
There are some more scenes to shoot next week, but when the cut is finished, I'll post it up here in the video showcase. Also, it's fairly negligible, but the cost of adapting an Ai mount lens to Canon is cheaper than the adapter for an FD mount by $20.