I just turned video auto-play on across the site. A couple of people emailed me recently to say it's annoying to click Next Lesson and then have to click again to start the video. That makes sense to me - if you're clicking on a video page, chances are you want to watch the video.

I don't really notice things like this myself because I don't watch my own videos very often. But when I'm on a site like YouTube and click a video, I expect it to start playing.

Let me know what you think. If enough people find auto-play annoying, I'll add a setting so you can choose whether videos start automatically. That will take a little extra work, so I won't build it unless there is enough interest.