Music From Seemingly Nowhere

[Lynn_M]

I've just been listening to a Youtube clip, which lasted for about 4 minutes. About a third of the way through, the clip restarted, whilst the original music that I was listening to continued playing

Where did this come from? I had no way of closing down the interloper without closing everything down (the way that I dealt with it the last time it happened), so I closed down the tab that I was originally listening to

The interloper didn't have a tab of its own, nor was a second window opened. How did this happen? I'm using a Windows 7 computer and I'm using Google Chrome as a (whatever it's called)