The checkbox is present in Twitter's main settings page (the one you land on immediately after clicking "Settings", not a subsection) and is also above-the-fold

The checkbox is present in Twitter's main settings page (the one you land on immediately after clicking "Settings", not a subsection) and is also above-the-fold. Also, I just found out he said a few months ago: "I was carrying my iPad, looking at the still image on the video and, without thinking, touched the PLAY button." So it seems he's aware of it.