I don't understand why any copyright holder could prefer removing his/her audio track to simply slapping some ads and trying to monetize the fact that someone, somewhere, likes their song. But what I do know is that YouTube has brought forth a number of interesting memes and phenomenons which will die out if this new audio muting practice continues (and spreads to music from other labels, not just Warner). Here are some of the obvious ones:
1. No more RickRoll (or any other authentic viral videos with copyrighted music)
By this, I don't mean the actual rickroll, that is, tricking people into clicking on a link with Rick Astley's song Never Gonna Give You Up. I mean all similar, past and present jokes and memes that use a popular, copyrighted audio tune. Whether you like the RickRoll jokes or not, you've got to admit that the world is just a tiny bit more boring place without them.
Sure, some viral videos don't use copyrighted music. But many do: Numa Numa, Evolution of Dance, and the Prison Inmate Thriller Video are just some examples. From now on, only big companies like Sony or Reebok will be able to afford using certain tracks for their annoyingly-fake viral-video guerilla-marketing campaigns, while the rest of us will be stuck with silence or YouTube's AudioSwap library. No, thanks.
2. No more anime music videos
I'm no anime buff so I won't try to explain the roots of this phenomenon, but for some reason anime fans like to use popular music tunes as background for original or user-edited anime clips. Guess what will happen to most of these on YouTube?
3. No more movie remixes
Another popular meme (which you may or may not like, but that doesn't mean that it's not popular) is dubbing clips from movies with popular audio tracks. A good example is the movie 300, which has been remixed with practically every metal band in existence; see here, here and here. This practice is also likely to all but disappear if users won't be able to use the coolest tunes.
4. No more Guitar Hero/Rock Band videos
Yup, you can't actually post a video of yourself rocking to your favorite Guitar Hero or Rock Band tune: you don't have the rights for that. Sounds stupid, since most of the fun in these games comes from playing with other people and comparing your skills with theirs? Absolutely. But what can you do: if there's music involved, the industry will shut it down although it's making them millions of dollars.
5. No more dance videos
Yup, you can't dance to popular tunes and put up a video of yourself doing it any more. You know all those videos of people acting stupid to Rihanna, Britney Spears, or some other popular song? Forget about those. Your 4-year old kid dancing to Madonna's latest single? Sorry, your kid will have to dance in silence.