Mark W is a case in point (positively) about how myths can get started. Someone hearing about his result (and not fully reading what he wrote in his post) could easily get the impression that you don't have to pay for "art" videos or if it's not for profit. A myth I've seen posted as "copyright law" on other forums. Mark's case was the publisher being generous.

Mark's done the right thing for this sort of project, contacted the copyright owners directly but for commercial projects this isn't always the cheapest way since the copyright holders often ask for silly money.

I worked on a low-budget feature a few years ago. The film was edited and finished.... and is still sitting in a vault. All because the producer cocked-up with the soundtrack. The movie was filmed for specific music and the producer got the reply "no problem, we'll sort out the fee after you've finished the film" and the producer (twat) assumed that it had been sorted. Needless to say the amount the copyright holder eventually asked for was way, way above what had been allowed for in the budget (they demanded a cool million, thus doubling the cost of the production) and it scuppered the movie.

Be warned.