I was going to do a quick answer with Movie Licensing USA - but when I went to grab the URL - I see that they are Swank. I'll look around to and see if I can find any others. We use them also.
We have always gotten our Movie Licenses through Swank movie licensing. This year, we are considering showing a few classics from the 60's and 70's like Frosty the Snowman, Santa Claus is Coming to Town, and the cartoon version of the grinch.
Swank does not have those movies as ones which they represent, and googling has yielded nothing. I can't imagine these are now " public domain" and fair game for school showings. Does anyone have any info on what other companies are out there, from whom I may have to get a license ? thanks