In iOS 10+

Apple finally enabled the attribute playsinline in all browsers on iOS 10, so this will work seamlessly:

<video src="https://stackoverflow.com/questions/19521667/file.mp4" playsinline>

In iOS 8 and iOS 9

You can work around this issue by simulating the playback by skimming the video instead of actually .play()‘ing it.

In short, use iphone-inline-video, it takes care of the playback and audio sync (if any), and it keeps the <video> working as it should.