Kit Walsh has an important perspective on Electronic Frontier Foundation, “Copyright Law vs. Internet Culture”. This essay is part of “Fair Use Week”.
The essay mentions the practice of mixing music and other media, creating derivative works. It also mentions that amateurs often don’t have the resources to defend themselves in court for cases that they could probably win. This applies to copyright as well as defamation (SLAPP) and remember a few years ago we had to deal with copyright trolls like Righthaven.
There is a culture in music and film industries to extract every drop of profit from some works. That’s partly because larger businesses in media and film are in someway funded by investors or sometimes donors who may believe owners have a fiduciary responsibility. That’s also because the more “popular” parts of the media generally claim that they employ more people, and can credibly argue that (union and guild) jobs are at stake. 20th Century Fox, particularly, states how many people it employed in the copyright notices on every studio financed film, often claiming it sponsored more than 10000 jobs.
I see a lot of people recording dancing at discos. Even that has gotten a little more problematic in recent years given privacy concerns, but I almost never post homemade video with disco music on YouTube out of copyright concerns. It’s a little silly, as the practice wouldn’t reduce owners’ incomes or threaten jobs. It would be difficult in practice to request and get permission for every such video.