Any particular reason why you need this Youtubed when Muppets Take Manhattan is available on dvd and not exactly hard to find - if you don't already have one already in your home? I mean finding a second hand or cheap copy can't be that hard.
Youtube is great but shouldn't be used as a crutch for what basically comes down to a form of "socially acceptable piracy". Different companies take different approaches to having their property put up when that same product is available officially to purchase. Just because Disney, Henson, and SW have largely been hands-off doesn't mean it's right.
I don't want to seem like i'm on some grand soapbox - heck i'm heavily into tape trades myself - but i (and most major tape traders) draw a line between stuff that's rare or hard to find that's not been officially released on video and stuff that can be bought - the sales of which SUPPORTS THE COMPANY AND GIVES THEM THE FUNDS TO DO MORE STUFF. Just because Youtube has this "everyone does it" vibe and has become as large and commonplace as things like ebay, amazon, and google doesn't mean that "anything goes". The point here is if someone wants a video of something that has been OFFICIALLY RELEASED and hasn't since become rare or unattainable, they should put their money where their mouth is and buy the product instead of having someone Youtube it, tape trade it, Hulu it, Myspace it or any other way of copying a video that can very easily (and ethically should) be legally purchased.