With document-gesture-activation autoplay blocking enabled, if you two-finger scroll, we'll activate the document. This is because we activate on touchend: https://searchfox.org/mozilla-central/rev/588d8120aa11738657da93e09a03378bcd1ba8ec/dom/events/EventStateManager.cpp#886 I don't think we should activate on touchend, or at least we shouldn't if no move happened during the touch. STR: 1. In Nightly, set media.autoplay.enabled=false and media.autoplay.enabled.user-gestures-needed=true. 2. Open http://pearce.org.nz/video/autoplay.html 3. Once the page loads, attempt to two finger scroll on your laptop's touch pad. 4. After a few seconds, the page will call play() in a timeout. Expected result: video doesn't autoplay. Observed result: video autoplays.

I seem to have been mistaken. Touch events on desktop do not seem to activate the document. D'oh!