3. Poster
The poster attribute (poster="#") should always be supplied with the <video> element. This attribute takes a URL as its value, which should point to an image that is displayed in place of the video until the visitor elects play the video.
Single-Source
<video src="#" poster="#" width="..." height="..." preload controls ></video>
Multiple-Source
<video poster="#" width="..." height="..." preload controls>
<source src="#" type="">
<source src="#" type="">
</video>
Note The image should be the same width/height ratio as the video element.
