flv files served from media.radiosai.org using the JW FLV media player appeared to be broken - not working from any of the machines at the studio. Then all video sites appeared broken! Including youtube, google videos and all the players listed at Wikipedia. Obviously this was unlikely. Checking the flash version number using this page, found that the videos were working fine in Linux with an earlier version (9.0.xx) of Flash plugin, and also with the latest 9.0.124 version. Maybe the 9.0.115 was the one with the problem. Or maybe not. Also found a post with various workarounds for flash video problems. And running the flashutil from c:\windows\system32\macromed\flash\ followed by a machine restart worked for the studio machines. Manual download and installation might have caused some problem, which this util might have cleaned up.
Edit: After a restart, my firefox again had the same problem. This time, tried the "acceleration toggle" trick - turn hardware acceleration off and then on again, using the settings option available by right-clicking on the video, restarting the browser each time. And it started working again.