Fix the stop-start playback on iPhone and iPad

Watching on an iPhone or iPad and the video kept stalling, staying silent, or just refusing to get going? That's fixed. On those devices you now give the video one tap to start it, and from there it plays through with sound like normal. No more fighting with a player that won't wake up.

This one came straight from learners on Apple devices, who ran into it far more than anyone should. It turns out Apple doesn't let a video start playing with sound on its own on iPhones and iPads, no matter what we do, so the old auto-start was quietly getting blocked. The single tap is the way around it, and now the rest of the experience just works.

And there's more good news on the way: we're building a proper iPhone and iPad app, where this whole thing disappears. In the app, videos just play, with sound, no tap needed. So this fix smooths things out on the web today, and the app will take care of it completely soon.