I have always loved Casper the ghost. I have gotten my kids into Caper too which is fun for me because I get to sneak in and watch the shows with them. We have an annual tradition of watching Casper Saves Halloween every year on our satellite tv from directstartv.com. It is not a long movie, maybe 25 minutes long. It is just the right length for your kids with short attention spans.
In the movie Casper dresses as a real boy and goes out on Halloween. The only kids who will go with him are a group of orphans. The mean ghosts try and ruin Halloween, but Casper and the kids stop them and save Halloween. The story line is cute and There are some cute songs through out the program as well.
The animation is a little dated and my kids did make a comment on that at first. But I explained to them that there weren't always computers and that cartoons used to be drawn all by hand. This interested them and now they decided that they want to draw cartoons too which has been a lot of fun.