Personally I think that's a bit of a stretch, but I'm not trying to say the show isn't great. While scientists could learn from their format (providing videos of their experiments, for instance) I wouldn't say that the mythbusters have advanced the cause of science at all. Would you say that the TV show Bill Nye the science guy advanced the cause of science? Science education he has definitely advanced the cause of, but science: not from the TV show. Similarly, I think the mythbusters have advanced engineering education tremendously, specifically television engineering education.
If you think they have actually advanced the cause of science, I would love to hear why. I'm not trying to be a jerk, I'm just speaking from having watched a few episodes, so I definitely could be wrong.