Firefox can use a (built-in) HTML5 media player to play media files without the need to have a plugin like Flash installed.

See also:

• https://blog.mozilla.org/futurereleases/2015/10/08/npapi-plugins-in-firefox/

Is there away to disable the (built-in) HTML5 media player?

You can set these prefs to false on the about:config page.

• media.windows-media-foundation.enabled
• media.directshow.enabled

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

• media.windows-media-foundation.enabled , is not listed in about:config
• media.wmf.enabled is the listed , is this the same?

I think the preference names for Windows changed recently. wmf most likely stands for Windows Media Foundation, but that doesn't seem to be clearly documented.

Anyway, are you sure you don't want any HTML5 videos anywhere? If you just want to control when they play, you could try toggling this preference:

• media.autoplay.enabled

jscher2000

When Flash player is enabled. On some websites, it sticks the scrolling and when replying in message fields the cursor comes and goes. This effects all the tabs that are open.

My thinking was to disable Flash player which fixed the above problem. But when I disabled Flash player on some websites the video ADs still played. So, I was thinking whatever was creating the flash player problem, was a competing video program. That is the reason why I wanted to disable HTML5 video. Then re-enable flash player. To see if that would fix the flash player problem.

Maybe it would be better to not use Flash player unless needed.

Did you try to set media.wmf.enabled to false?

There are more media.*enabled pref for specific media types.