Stop Firefox YouTube from auto-loading videos (HTML5)

Question

I am using Firefox version 36.0.4 which has HTML 5 video. How can I stop it from autoloading videos in YouTube. For example, when I got a YouTube page, videos will immediately start playing. Also, When I watch a video on YouTube, after it is done, somehow YouTube decides to play ANOTHER video which I did not pick and then start to automatically play it. I find this extremely annoying. How can I block this behavior?

Please note that solutions from Is there any way to disable a YouTube video from automatically starting in Firefox? don't work because they are about Flash videos which isn't the case here

Solution

As of Firefox 69, you can now configure Firefox' settings to block all or specific websites from autoplaying videos.

To always allow or disallow autoplay for all videos or media with sound:

1. Click the menu button and choose Options.
2. Select the Privacy & Security panel.
3. Scroll down to the Permissions section.
4. Go to Autoplay → Settings. Default for all websites: Block audio is the default setting. Set this to Block Audio and Video to block videos too. Or set this to Allow Audio and Video and you can configure blocking autoplay on a per-site setting, instead.

Youtube.com's site permissions will look like this if set to block video autoplay. You can also opt to set the autoplay permission to allow autoplaying videos for youtube.com only and not other sites.

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Firefox versions prior to 69 can use the YouTube High Definition extension (also a Chrome extension) to stop YouTube from auto playing videos, among other features:

^{This is from another answer of mine in Is there any way to disable a YouTube video from automatically starting in Firefox?}

Comments

[vembutech]

Stop Tube effectively prevents HTML5 videos from buffering and auto-playing. This feature is used for conserving your bandwidth. Its main ability is to halt buffering.. Also, the add-on does not require you to restart Firefox, simply install it and you are good to go.

[Vinayak]

This is how you prevent YouTube from automatically playing videos that you did not choose (recommended videos)

[galacticninja]

@TylerDurden Try one of the extensions I posted as an answer in that question. AFAIK, they will work whether YouTube uses Flash or HTML5 to show the video.

[Tyler Durden]

@galacticninja I am going to try all the answers and pick the best one. Vinayaks comment does not work for the reason I already listed.

[Vinayak]

@TylerDurden I just tried turning Autoplay off and refreshing the YouTube page and it was still turned off. I'm using Chrome with the HTML5 player. Are you clearing your browser cookies on exit or using third party tools like CCleaner to do that? If that's the case, your Autoplay setting will not be honored.

[Vinayak]

@TylerDurden I tried it again with Firefox 36 this time and it's still working as expected. Autoplay doesn't turn back on when you refresh the page or watch another video. My guess is you're deleting browser cookies which sets Autoplay back to its default setting which is 'enabled'.

[José]

OP's question is about disabling the loading/playback of HTML5 videos as soon as the page is open, and not about the new "Autoplay" feature of Youtube, which opens a new video after finishing playing the current one.

[Vinayak]

@screened The OP's question is about both those scenarios. My answer solves the second half of the question. I shall update it with a solution to the first half when I come across a solution for that as well.

[José]

Ah, I hadn't read it carefully. The part you'd answered is off-topic here though. It should be moved to webapps.stackexchange.com , if there isn't a post about it there already.