A few days ago, this problem appeared. When I play a Youtube video, I get sound but no picture, only black screen. It is a HTML5 video.
I have turned off all related addons, and the problem is still present.
What can cause this?
These are my specs:
HP G5 255 (laptop); 15,6 inch 1080p display; AMD A6-7310 APU with AMD Radeon R4 Graphics × 4 (1 GB allocated to iGPU) Gallium 0.4 on AMD MULLINS (DRM 2.49.0 / 4.10.10-041010-generic, LLVM 4.0.1), Mesa 17.2-dev; 12 GB DDR3L 1600 MHz (4 + 8 GB); Ubuntu 16.04 64-bit; Firefox 53.0.3 (64-bit)
It has been fixed by these steps:
Simply restarting (closing and starting) Firefox in normal mode had no effect.
Edit: I have just noticed that Firefox is now updated to version 54. Maybe that fixed it. But I don't remebmer getting any FIrefox updates, nor did I get any notification to restart FIrefox in order to update.