Youtube, Firefox Portable: Picture randomly freeze at 720p60 and completely freeze at 1080p60 and beyond

aor999

Honorable
Jun 28, 2017
12
1
10,565
I don't know if this board is suitable for this topic, so admins can move it, if it isn't suitable.
Anyway: I'm watching gaming videos of Sonic The Hedgehog series through Firefox Portable, and any video that would be available at 60fps, the picture would freeze randomly at 720p60 and completely at 1080p60 and beyond.
Why this is happening?
 

aor999

Honorable
Jun 28, 2017
12
1
10,565
I tried the same videos at 1080p60 through Pale Moon, and they worked fine without picture freezing. So it don't looks like related to my PC specifications. And yes, my display adapter supports 1080p, which is the native resolution of my Samsung SyncMaster T220P LCD display.