Sure, but most people want to use popular music, as a result the most popular video editor for istagram has licensed popular music* from the majors. This is not a novel business.

*http://www.digitaltrends.com/social-media/storytelling-socia...

Interesting. That doesn't scale though, because you can't upload the same clip to YouTube without it being flagged. Having rights to backing music is not great as a differentiator for a social network.

"Just sharing with friends" is still copyright infringement. The owner of the copyright--not you--gets to decide how the work is reproduced and distributed, unless you have a defense like fair use. (I'm not saying this is always a good thing; it's just how the law works.)

It's not Facebook's responsibility to enforce this absent a complaint from the copyright holder.

Yeah it is, but in the scheme of things it's pretty benign. I couldn't purchase the rights to use the song even if I wanted to, and I'm only using a portion of the track, so I'm not actually denying them income.

Yeah, but you're probably not willing to pay enough to make it profitable if your videos are for personal entertainment only rather than aiming at any kind of significant audience.

From the data I've found Pandora pays around 0.2 cents per stream. I'd be more than willing to pay that (or even 10x as much) to use a track on a video that a couple of hundred friends might see.