My organisation recently published a number of videos on the public website (EDIT – have removed the link as the videos have been taken off now). Those videos started automatically as soon as the page loaded. The problems with this are:
Automatically playing audio on a webpage is usually an action which the user will not expect. It is therefore, at the very least, an irritation, especially if the user is in an environment where this is not appropriate.
At worst, though, the audio may conflict with other audio that the user is already listening to. That might be music, or perhaps another video. But far worse, it could be a blind user’s screen reader software, and the resulting conflict would make it very hard to browse that page to pause the video or mute the sound.
By: James Coltham, 2009