This extension has a major flaw as you cannot set your own wallpaper due to then you upload the file as .mp4 it won't pick it up 2 second issue is that the firefox button to use so that i can upload custom wallpapers doesn't work as it won't pick up the fact that i have already download the extension and i am signed in.

Please fix this.

Simply loved it! It didn't work out of the box on Firefox Developer Edition, but I found a way. Appreciate your work! Thank you!