S.H.
Good luck with watching the movie for the kids.
I mean it in jest... because, when my kids have playdates.... and I have a movie for them, even one they picked out themselves... they NEVER EVER.... sit there long enough to actually finish watching the entire movie.
So it is moot.
Have a puzzle.
Crafts.
Board games
Legos
Play Doh
lots of paper for drawing on and crayons/colored pencils
Paper plates to make stuff out of.
Put it all out.... "buffet" style for the kids. Makes it more fun looking and interesting etc.
Get them goofy "party" hats to wear for fun
Boxes they can make stuff with.
Have a lot of beach blanket type stuff on the floors & pillows... to make it fun, and they can pretend picnic and eat there in the room where the kids will be at. Perhaps?
Treasure hunt in the room where you will all be.
Hence the adults can still view the game on the tv too.
5 year olds, will have different interests than the 8 year olds.
And different attention spans.
I have a 5 and 9 year old.
OH! This is another fun one my kids like: Get some helium balloons. And my kids like playing it by tossing/batting it around the room to each other. And it really wears them out and they sweat!
You will have 5 hours of keeping the kids occupied.