I also encountered this problem yesterday, on Jaunty with Firefox 3.0.11+build2+nobinonly-0ubuntu0.9.04.1 and flashplugin-nonfree 10.0.22.87ubuntu2
The URL I encountered the problem on is http://www.imdb.com/video/imdb/vi2784428569/
I have no problem with YouTube videos. I did turn off AdBlock Plus as imdb.com suggested, but it did not help.
I also encountered this problem yesterday, on Jaunty with Firefox 3.0.11+ build2+ nobinonly- 0ubuntu0. 9.04.1 and flashplugin-nonfree 10.0.22.87ubuntu2
The URL I encountered the problem on is http:// www.imdb. com/video/ imdb/vi27844285 69/
I have no problem with YouTube videos. I did turn off AdBlock Plus as imdb.com suggested, but it did not help.