Disable Video Buffering in Firefox

Solution 1:

Prevent auto-pay:

Type "about:config" in the address bar, hit Enter, and click through the confirmation screen. Search for a setting called "media.autoplay.enabled," then double-click to disable it.

Prevent buffering:

Set media.cache_readahead_limit to 0.

Set media.cache_resume_threshold to 10 and media.cache_readahead_limit to 30.

Now you won't auto-play, if you choose to play a video you won't buffer much; if you play faster than you downloaded (empty your buffer due to high resolution, or low compression due to complex motion) you'll get the spinner, so increase the values to avoid that.

If you never want to watch videos over cellular data connections you can choose in the settings to use Wi-Fi only, but that didn't seem to be what you were asking.