I think to get it work you have to do a few things.
1) Close out your browser completely during a video.
2) The video must still be playing.
3) The video URL must end in a 1, 3, 6, 7, 9, Q, U, P, F, G, K, C, or V.
4) You must have closed out of the browser during the sixteenth second of every minutes.
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Xbox GT: PrivateBiscuit1
Down with Zhang. Let there be Biscuit!