Autoplay video refers to a video display mode by which the advertising video is played when the advertising creative is displayed or visible on the page or when it is flown over by the mouse.
With autoplay mode, a video starts to play in the email client as soon as the email is opened or for an ad, as soon as it is displayed on the webpage.
In some cases, the sound can also be enabled during the autoplay.
The autoplay feature obviously plays significantly on the number of considered ad video views, but it also raises questions about the real impact of the advertising message.
The autoplay mode is generally considered intrusive. It also may cause disturbance and bandwidth issues.
For an illustration of an intelligent use of the autoplay mode, see Facebook video autoplay.