Nokia Lumia 920 - Windows 8.1 - Phone has somehow changed versions of songs????

[WPCentral Question]

I was just listening to my music using Nokia Mix Radio when I noticed that the song I was playing sounded different to how it usually sounds. I actually converted this song from YouTube on my PC and copied it onto my phone (my bad!) so I don't understand how the phone just managed to change it. I came to the end of the song when I suddenly heard cheering? I'm so confused! I have played this song on my phone for ages and this has never happened before. I opened Xbox Music and played the song there to see if Nokia Mix Radio was the problem but the same thing happened there; I heard cheering at the end of the song as if I'd converted a live performance of the song and put it onto my phone... Which I definitely did not! I think it has something to do with the update to 8.1 but I'm not entirely sure. Anyone know what's happened here?