You'll see this message more often on YouTube, especially if you're trying to watch MTV videos. Viacom demanded YouTube to remove more than 100,000 videos that use content from Viacom's companies.
"After months of ongoing discussions with YouTube and Google, it has become clear that YouTube is unwilling to come to a fair market agreement that would make Viacom content available to YouTube users."
It's interesting that Google has a deal with Viacom that allows web publishers to display streaming video ads and video content from MTV Networks on their own sites (in a limited test, for now). Viacom also offers a lot of content in Google Video, but not for free.
Viacom is disappointed that YouTube didn't implemented the content identification system that will allow YouTube to see if a video contains fragments from Viacom, for example. This way, Viacom would get some money from the ads displayed by the online video site. "YouTube and Google retain all of the revenue generated from this practice, without extending fair compensation to the people who have expended all of the effort and cost to create it," grumps Viacom.
It seems that YouTube respected their demands and took down a lot of videos. Do a search for [vh1 live] to see for yourself.