RIPE has a nice tool the shows the BGP route convergence. Here's a predefined query:
http://tinyurl.com/2y69mv (Java needed)

AS36561 is YouTube, AS17557 is Pakistan Telecom. Click the play button and see that starting at 18:47 hours the routes moving over to Pakistan telecom. moving on, at 20:07 hours, you can see the routes start to fix themselves. By 21:04 there are no routes left going to AS17557

http://www.renesys.com/blog/2008/02/pakistan_hijacks_youtube.shtml
has a writeup.