Problems playing HTML5 Video

[Brundle]

Hi,
I have a problem playing HTML5-video. I can hear the sound, but I only get a black rectangle where the video should be. What's strange is that when I start Pale Moon in safe mode, it plays video just fine, so I know the browser is perfectly capable. Here's what I've tried:
- Downloaded Pale Moon Portable 26.5.0 (64 bit). This is a fresh install, no options changed, no add-ons installed. I realize portable is not recommended, but it's just so much easier when playing around with different settings as I can just delete the folder and restore a fresh one to start over. I've even played around with the installed version, the results are the same.
- When I start the browser in safe mode it plays video just fine.
- When I start in normal mode, black screen, sound only.
- I've tried checking all the boxes on the safe-mode start screen and clicking "make permanent and restart" but still only sound and no video.

So I guess my question is this: What exactly is it that Safe Mode disables in addition to add-ons and the other stuff on the startup screen?
This is the video I've been testing with: https://www.w3.org/2010/05/video/mediaevents.html
In case it's of importance I'm on Windows 7.

Any and all help appreciated!

Regards,
B

[coffeebreak]

The linked video plays without problems for me, picture and sound, using PM 26.5 Portable on Windows 7 x86.

Safe mode disables (in addition to addons) visual/UI customizations, the javascript compiler, and hardware acceleration. Explained in more detail in this MZ-kb article: Safe Mode. You might try disabling hardware acceleration:
Menubar -> Options -> Advanced -> General tab
or
PM button -> Options -> Options -> Advanced -> General tab

[Brundle]

Thanks a lot for your insight!

It turned out to be a combination of hardware acceleration and an extension "foxyproxy" which I had misconfigured. Now everything works perfectly!