Since the late 70s and well into the 80s currently version 88 of Firefox I had a problem with most videos displaying the following message:
"This video This video cannot be played because of a technical error.(Error Code: 200001)"

I have no proxy set and all drivers are current.
Researching I found many having same or similar problems but nobody having a solution.
That was until I came across a locked and archived forum thread: https://www.reddit.com/r/techsupport/comments/aday21/video_error/

The last reply, by "SlickStretch" was the correct answer and solution.

"solved by disabling the extension: 'Disable HTML5 Autoplay.' Try disabling/removing this extension or any similar ones."

This used to work fine, but in the last few days it has started BLOCKING videos in Facebook and newspaper sites. Have to disable it in these sites if I want to see videos, but then they autoplay, which is precisely why I NEED the extension! The extension is now almost useless.

Doesn't work any longer on Youtube.

Don't work on morgenpost.de
funktioniert nicht auf morgenpost.de

It did not disable autoplay on Tubi. Nothing else has stopped autoplay on Tubi without breaking manual playback.

Does not disable autoplay, nor preloading.

Addon not bad, but would like to exclude some domains. Unfortunately it does not work. Must switch it off manually, if needed. It sucks.

You had ONE JOB...

It doesn't bloody work!

BREAKS VIDEO on some sites .. espesially IMDB
I dont advise anyone to install this addon unless it gets a major update

Diese App blockiert unter Firefox in GMAIL beim Schreiben von Mails das Drop-down-Menü der vorhandenen Kontakte/Gruppen. Man kann Kontakte nur mehr einzeln, händisch eintippen. Aus diesen Gründen ist das Add-on unbrauchbar.

Works but errors videos... try 'Video Autoplay Blocker' addon. It works good in my testing so far.

It puts a 'Play Video' in top corner.. WORKS GREAT and I checked the code with 'Extension Source Viewer' and it is clean, no spyware in it. 5 STARS!

Doesn't work, both Washington Post and Travel Advisor blow right past this app.

Not working in FF 70.0.1 (64-bit) on any of the multiple offenders' websites I have checked: MSN, Yahoo, CNN, etc... All videos autoplay as annoying usual.

Doesn't prevent udemy.com from preloading every video.

Does not work

Doesn't work

Several issues with this addon that made me uninstall it:
- It simply doesn't work for some news websites that autoplay HTML5 video.
- The options menu displays a table of exceptions you've added, but it's always blank and can't be edited.
- It doesn't have any way of adding global exceptions for things like Bandcamp, where each artist has a domain prefix you must allow manually to get tracks auto-advancing.
- Most critically, this disables audio in many video conferencing web apps like Google Meet, and disabling the addon for them doesn't always work.

I have to DISABLE or REMOVE this extension in order to allow preloading to occur. "Pause Autoplay" and "Disable Preloading" check boxes do not function for individual sites.

Doesn't work, unfortunately.

No matter what, it'll always prevent a page from preloading. Even when you set a page to preload. Which prevents proper use of Youtube.

Causes many video streams to fail, throwing the following JavaScript error: "This video cannot be played due to a technical error.(error 200001)"

Unfortunately, this add-on is not doing anything at all for me in Firefox 65.0.2 on Windows7 64-bit. I like how it has options for both "autoplay" and "pre-loading" and that it is designed for all HTML5 video sites.

Other reports suggest that it works for some people, but not for others. Too bad, as the concept is useful and the interface is well-designed.