iOS 10 update
The ban on autoplay has been lifted as of iOS 10 – but with some restrictions (e.g. A can be autoplayed if there is no audio track).
To see a full list of these restrictions, see the official docs: https://webkit.org/blog/6784/new-video-policies-for-ios/
iOS 9 and before
As of iOS 6.1, it is no longer possible to auto-play videos on the iPad.
My assumption as to why they’ve disabled the auto-play feature?
Well, as many device owners have data usage/bandwidth limits on their devices, I think Apple felt that the user themselves should decide when they initiate bandwidth usage.
After a bit of research I found the following extract in the Apple documentation in regard to auto-play on iOS devices to confirm my assumption:
“Apple has made the decision to disable the automatic playing of video
on iOS devices, through both script and attribute implementations.
In Safari, on iOS (for all devices, including iPad), where the user may be on a cellular network and be charged per data unit, preload and
auto-play are disabled. No data is loaded until the user initiates it.” – Apple documentation.
Here is a separate warning featured on the Safari HTML5 Reference page about why embedded media cannot be played in Safari on iOS:
Warning: To prevent unsolicited downloads over cellular networks at
the user’s expense, embedded media cannot be played automatically in
Safari on iOS—the user always initiates playback. A controller is
automatically supplied on iPhone or iPod touch once playback in
initiated, but for iPad you must either set the controls attribute or
load() methods are inactive until the user initiates playback, unless the
load() method is triggered by user action (e.g. a click event).
Basically, a user-initiated play button works, but
onLoad="play()" event does not.
For example, this would play the movie:
<input type="button" value="Play" onclick="document.myMovie.play()">
Whereas the following would do nothing on iOS: