So about a week ago I got the 15" rMBP with the dGPU, and whenever I watch YouTube videos, the little rectangular video player will be black fro 2-3 seconds but the sound still plays. It's almost like a lag, but like I said the audio still plays. After 2-3 seconds the video plays as it should. Does anyone have these issues or any suggestions on how to fix? It's not detrimental but if my $200 Toshiba doesn't have a problem.....