The Video that won't Stay Linked

In September, I watched Fame and posted videos relating to it. You can see that here. However, looking at this post is almost pointless because one of the videos I have posted six different times and it refused to stay available. It always exists for a while and then it disappears from YouTube saying that there was a copyright problem and the video had been removed. This makes me wonder: What do you have to do to put a video on the Internet and not interfere with copyright laws? I love having all the videos we do on YouTube, but most of them aren't probably legal or shouldn't be. I don't think that videos should be posted of people's music or anything else because it denies the creator the money they would have gotten had people been forced to buy them off something like iTunes. As an aspiring musician I understand why the artist that made "Hold your Dream" in Fame would want the video removed so they can make money off the sale of it, but why haven't any of the other videos that are on YouTube been deleted? If we are going to have a rule and only partially enforce it, what is the point of having the rule? There are some videos that can't be embedded and that makes since; if the video can't be taken to another sight then it can be more selectively observed. But the video I posted was perfectly fine to embed; it simply disappeared from YouTube after I did. I feel that YouTube should make a more consistent rule on what can and can't be put on its sight because of copyright laws. It would be more fair to artists and those of us embedding videos.