Video drivers : 19.6.3
Chrome latest stable version: 75.0.3770.142 (tried with edge same thing happens)
Gigabyte RX560 2GB (stock settings)
W10 1903 with latest updates
If i play youtube video in full hd resolution video codec : vp09.00.51.08.01.01.01.01 (248) / opus (251)
my gpu usage goes about 10% (video playback works fine).
but if i play video in full hd resolution video codec: avc1.64002a (299) / mp4a.40.2 (140)
my gpu usage is 98-100% video decode and video lags.
Before i installed 19.6.3 i used DDU (uninstalled it from safe mode)
I can confirm this on 19.6.2 also, even through MPC-BE on HEVC content. The situation does seem to be resolved on 19.7.5. Funny thing is though, I don't recall there ever being much in the way of GPU activity during video decoding at all prior to W10 1903. Unless I'm mistaken? I thought a different part of the GPU was responsible for video decoding, not the main core.
Edit: It's specifically related to "GPU 0 - Video Decode" in task manager, not "GPU 0 - 3D", so they are separate.