Github user xuyouyang commented on the issue:
https://github.com/apache/incubator-weex/pull/1051
NO.
The poster attribute specifies an image to be shown while the video is
downloading, or until the user hits the play button. If this is not included,
the first frame of the video will be used instead.
You can see this "https://www.w3schools.com/tags/att_video_poster.asp";
It is a attribute in HTML <video> tag---
