Those videos in Germany are blocked because of a conflict between the GEMA and Youtube. The GEMA wanted much more money from Youtube. Youtube didn't want to pay. So the GEMA demanded the blocking of tons of videos in Germany, which Youtube followed.
http://en.wikipedia.org/wiki/Gesell...ungs-_und_mechanische_Vervielfältigungsrechte
The GEMA represents nearly every international famous singer or group in Germany, so practically all official videos of them aren't working and fanvids, who use their music are often blocked, too. Even videos from German singers and groups, like for example Tokio Hotel, are often blocked.
At least a lot of smaller videos sites still have all kinds of unblocked music videos. I think the GEMA targeted Youtube, because it is the biggest video site.