Firefox Knowledge Base
Disable Video Autoplay
Go to Settings
> Privacy & Security
> Permissions
> Autoplay
> Settings
.
Select Block Audio and Video
and click on Save Changes
.
Type about:config
in the address bar.
Set the following preferences:
media.autoplay.default = 5
media.autoplay.blocking_policy = 2
media.autoplay.allow-extension-background-pages = false
media.autoplay.block-event.enabled = true
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