Specs: Win 7 Pro, using Chrome, 6MB RAM
RealPlayer: Behaves. At peak times some occasional buffering moments, as would be expected. Other than that, it works well.
Flash: Attempted to watch an episode of Smallville at a time of night which is usually empty. So far (just over 90 seconds in) the player has had to buffer no less than six times.
Conclusion: Maybe the flash player will get better as users leave the site in frustration, leaving more bandwidth for those with more patience. As is often said, what is not broken DOES NOT need fixing.