Ran into an odd problem. I tried uploading a video from my Mac to YouTube. This is the first time I've tried to do this since upgrading the Mac to Snow Leopard (OS X 10.6). The problem is that YouTube doesn't even let me see the dialog box to upload a file from the Mac. You can see what the problem looks like in the screenshot above. This happens with both Firefox and Safari on the Mac.

I was able to upload a video file from a Windows 7 computer and Firefox without any problems.