Is there any way to disable a YouTube video from automatically starting in Firefox?

Solution 1:

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.

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:

Solution 2:

Probably late (just by 6 years!), but if you don't want to install an extension, you can use the Firefox configuration editor and change the media.autoplay.enabled value to false

Solution 3:

Starting with firefox 63, the preference setting to disable autoplay has changed as answered in Firefox support:

in about:config you can set media.autoplay.default

• to 1 in order to block automatic playback on all pages
• to 2 to decide on a per domain basis.

NB: In future release, this feature will be accessible in Options (source)

Solution 4:

FlashBlock can do this.

Solution 5:

Download Greasemonkey for Firefox.

Download the YouTube Enhancer userscript.

At the top of the window, there is an option where you can set automatic buffering to off or autoplay to off. Same consequence, but with auto buffer, you need to wait for it to buffer (no problem on fast internet anyway).

Also other goodies as well:

• loop
• kill stream
• loop between two set points
• change quality easily