That Donald Duck remix cartoon also reminded me of something I don't think I've mentioned before: despite its reputation as an extreme copyright hawk -- there's a reason "Disney lawyer" is a term all its own -- Disney probably cracks down less on YouTube postings of its classic material than almost any other company.
I won't link to examples for fear of jinxing it, but there are clips of Disney cartoons, or songs from Disney animated features, that were uploaded soon after YouTube got popular and are still there, years later. There are some that have gotten pulled, I'm sure; recent material quite rightly gets a harder time, and not all classic clips stay up forever -- though some of them may be due to account deletion (from other things that got pulled) rather than Disney complaints. It may be that they've done what other companies do and simply arranged to get YouTube to give them a piece of the ad revenue in exchange for keeping those clips up. I don't know the details, though I'm going to try and find out.
But if you compare it to Warner Brothers, it's a whole different thing: Warners is constantly cracking down on classic cartoon uploads, taking them down almost every time they appear. The few that are still there are exceptions, clips that WB hasn't noticed yet for some reason or another, or public domain cartoons. Disney either has a laissez-faire attitude about classics on YouTube, or just doesn't have a system in place for taking the stuff down.
Whether this is a conscious Disney policy or not, you'll be unsurprised to hear that I think it's a good policy. As I've complained many times, by taking its classic cartoons off YouTube, Warner Brothers cuts off its best hope of introducing young people to these films; they're constantly trying to figure out how to rebuild the Looney Tunes brand, but cracking down on uploads that get hundreds of thousands of views for these characters. Whereas kids who want to see Donald Duck can see him all over YouTube; there are some real Donald Duck cartoon uploads with millions of hits. That's got to be good for Disney's branding and marketing, even if it's not legal.