Sure, it just happened again.
I have Youtube running in a window on Chrome, and Music Bee open as well. Music Bee is open but not playing anything, a track is queued up but I haven't hit play or anything yet.
I watched half of a long video on Youtube, skipped around, and closed the window. As soon as I closed the window with the Youtube video in it, the track queued in Music Bee started playing.
This also happens in situations when a youtube video, bandcamp file, or other video/music file finishes playing in my browser and doesn't go on to another file (like next up in Youtube or the next track in bandcamp).
This is super annoying and I have to close MusicBee anytime I'm not using it.
Thanks!