When I set it to play automatically, it does play when I hit the page, but not when I return back to it. It does play again if I go back a few pages, then return (or if I re-open the book)
play-on-ipad-automatically.mp4 (3.5 MB)
Here's how it works (with tapping, and not set to play automatically). When I first tap the widget on the iPad, the document loads (and plays). If I tap the button, it plays again:
play-on-ipad.mp4 (1.1 MB)
Are you all on the latest version of iOS?