- access data: probably because the gesture is actually done inside the page you're viewing, so it has to be able to capture that
- clipboard: it was a feature requested, for gestures to be able to work with the clip board: https://addons.mozilla.org/en-US/android/addon/simple-gestur...
So just recently added for that reason
Curiously the blurb recommends "Quick Gestures" which presumably is a different gesture addon.