Youtube scans each audio upload and compares it to a database of copy righted material. It compares pitch, tone, and I guess some other stuff-length of the music is not one of the things compared. If your audio is found to be copy righted then based on the owners request a number of things could happen:
1. The owner allows the audio to stay with ads added to buy their music.
2. The owner allows the audio to stay but it can't be played in foreign counties or mobile devices.
3. The owner does not allow the audio to stay and the audio is muted.
3. The owner does not allow the Utube link to be share. This happened to me on one of the DG videos I did last year so I had to re-do the audio.
4. The owner sends the Feds after you.
If you haven't already you should receive a notice from Utube that you have used copied righted material.
The above comments are my own by what I have expierenced.
PS, you can down load an application to change the tone and pitch of copied righted material, it don't take much change to get it pasted the copy righted material data base search. At least that is what I've been told-not that I have ever done that to get around the copy right issue.