Where intermediaries and bots rule, de facto fair use (or at least tolerated use) may end up being whatever slips by the anti-piracy program. Experimenter Scott Smitelli reveals the following:
It is quite possible to thwart the YouTube Content ID system, but some methods mangle the song too much to be used in anything useful. . . . The most subtle approach is to use a resampling function, which simply increases or decreases the speed of playback. For these modifications, a speed increase of 5% or greater will work, as well as a speed reduction of 4% or greater.
No problem for some artists. Justin Bieber is basically unlistenable until you slow down his songs by 800%.