It's probably a coincidence, but just this weekend for the first time ever, I noticed my YouTube streaming at visibly lower quality (my provider is Cox). It happened all weekened, intermittently. Nothing else seemed slow, and numerous speed tests (both from official "speed test" sites including Netflix's own Fast.com, and by moving large files between my network and AWS) all showed well over 100Mbps. I don't know if it was being throttled somewhere, Netflix's service was overloaded, or if there was some other weird problem happening on my network that affected Netflix and nothing else. But it was bad enough that my wife who is usually oblivious to audio/video quality actually brought it up.