I would definitely place the Sci-Fi clips more in the silly category. Also, there's always so much going on, the atmosphere is so cool, no one focuses on just the movie screen the whole time. Sci Fi is one of my favorite places on property. We never miss going there no matter what. The atmosphere is just so amazing and original and we LOVE the food. Also, Sci Fi and Beaches & Cream have the best milkshakes in the WORLD. I don't even drink milkshakes when i'm not at Disney anymore, no other place compares.
I don't like 50's Prime Time as much as Sci-Fi but I still love it there - especially the Smores dessert! It is like stepping right into an I Love Lucy episode, the atmosphere here is so great too. If you tell your waiter that your child is easily upset, they will not do their usual shtick and make them eat their vegetables. That goes for anyone though, if you tell the waiter before hand that you're uncomfortable, they will not do what they usually do so that is not a worry.
Hope this helped!