Hulu will work for a few minutes before I get the beach ball. Other flash videos will play for a few seconds, then stop and never finish. However Netflix in Safari and the Hulu application work fine. I'm up to date on my flash player and Safari.
Well, this is the main reason Steve Jobs wants to help kill Flash, it pulls on too many resources and crashes Safari. You could try and make sure you have the latest version of Flash by going to Adobe's website and download it. Someone else may have another suggestion.
I had a love hate relationship with top sites. It seemed that launching Safari took longer, and my browser always froze when trying to open new tabs. It's much faster with it turned off IMO.