I had similar issues with YT mostly with new uploaded videos. I also asked similar question on some other forums. And I was told that depending on where you click a video on YouTube the video URL will pick up extra data in its URL.
For instance, if you go to CarscomTV Youtube page and click on Cars.com Super bowl Ad, the URL will be like this:
Although the actual URL is:
As you can see in the first link the extra information is separated by an "&" symbol. And sometimes, this extra information can disrupt the video URL.
So, first you have to make sure that you select only the info before the "&".
You also can add &sns=fb after the actual video URL.
I think the issue regarding no YT thumbnail pic appearing on FB is quite widespread.
Also, check out this: http://www.google.com/support/forum/...l=en&start=120
Hope it helps!
Last edited by Exulted; 25-02-2012 at 12:51.