It's been over 9 yrs since we went...my oldest daughter turned 9 on that trip, my youngest was almost 5. Well...my 9 yr old was terrified by the movie clips...didn't eat her meal, etc. My 5 yr old was fine. My oldest NEVER wanted to eat there again...so we haven't, lol. She's in college now, and we'll be taking a trip without her next February...and we're taking the younger one (14 yrs old) there--so we finally get to try it out again!
So...you know your kids best, if they're frightened by Ursula, the wolves, etc...I'd just wait until they're older to go...of course based upon my experience...maybe wait until middle school, lol. But, yes, you can check out the clips ahead of time online--if you really want to eat there, maybe even watch some of the clips online with them...see how they react in a safe environment...if they seem okay, take them, and tell them...these are the same clips you saw at home, nothing to be afraid of.