For visitors to my site, how can I tell if the "YouTube.com" domain is blocked by their work policies?

I'd like to embed a YouTube video on my site, but am worried that many members of my audience may have restrictions (for example, WebSense) blocking the YouTube domain. Is there some way I can tell if that is the case? Essentially I'd like to know, of my visitors, which are able to view the video I am displaying. Any suggestions welcome!

To follow up -- I'm less concerned that a user doesn't have Flash or the right version, as that is something I can track directly. My only concern is that YouTube is blocked. I am thinking an onError event attached to the object would get me the information I need, but I can't think of a way to test my theory :)

such restrictions could be so granular as to be on a PC by PC basis. There's no way for you to know who's restricted unless you get a complaint "I can't open the link!"

how about a less techny solution - a small sentence text link above or below the youtube frame box 'if you can't see this video click <li>here</li>' and it leads to page where you explain that they have restricted access because of their network settings. number of visits will actually show you who cares to see the video but can't. k.i.s.s.