Companies Blocking YouTube and Video Content

I have embeded a YouTube Video into a site of mine and that is all
working fine. But certain companies have blocked YouTube at work, so
when some one goes to the site all they see is an empty block.

Is there a way I can tell if a company is blocking the video (similar
to checking if some one has a flash player) so that I can display
alternative content?

I found this thread at http://stackoverflow.com/questions/286021/detecting-if-youtube-is-blocked-by-company-isp that describes some script that supposedly accomplishes this. I can't tell you about it's reliability, but it seems like it would work.

Good luck!