Reviews say that children love it but parents hate it - parents are smarter than kids and they are right. Some kids may just be amused by Fred's appalling behaviour but many will consider that if it is in a DVD and everyone says it's cool to act like this then they can do it too. I have worked with kids who act very similar to Fred - scream or fight or abuse until the adults back down. I was bemused by the behaviour - where did they learn to act like this? until one of them showed me his favourite movie - and there was Fred, acting just like them.
Do be cautious; are your kids laughing at what is truly amusing or are they excited by the possibility of breaking all the rules and letting off steam just when and how they want to? If they are excited by this idea, please make sure that they don't start acting it out in real life. Watch the videos yourself and if you see them acting like Fred, then tell them so and get them to stop