Rogen is occasionally funny in his movies, but after having to put up with his appearances on practically every television show leading up to the release of Green Hornet, I have serious doubts about him being long for the industry.
He was a chuckleheaded monstrosity on Letterman: he seemed stoned out of his mind. His Mythbusters special was half him guffawing and half him being a completely idiot jerk to the build team, probably due to a hangover. Or a huge ego. Or both.
This sort of half-stoned, half-jerk blabbermouthing may explain why most of his appearances in film are in his own/his buddies' flicks, and probably speak to somebody who won't be around much longer.
Personally, I think Lucas is one of the great tragedies of Hollywood. He's someone who started out with such promise, whom millions ? including myself - idolized when we were kids, who eventually lost all that promise and seems to surround himself with yes men who never question his lousy ideas. But I don't believe he is this stupid. And all things being equal, I wouldn't be surprised to find out that the simpler answer is (take your pick):
1. He was talking about an Indiana Jones plot and Rogen was too stoned to realize it.
2. Rogen was so stoned he hallucinated the whole thing.
3. Rogen is just stoned.