Blurring and blurring of pictures on video in the internet

Guys who had a similar problem: a week ago, the quality of the videos was excellent at 1080, and now when you watch the same YouTube and set the quality to 1080, the picture blurred, although the picture in the Witcher third at ultras is perfect.
Video Card: GIGABYTE GeForce GTX 970 1114Mhz PCI-E 3.0 4096Mb 7000Mhz 256 bit 2xDVI HDMI HDCP
Monique: AOC 2269WM 1920 x 1080 60Hz