See below link
https://www.qualtrics.com/community/discussion/comment/2633#Comment_2633
Hello
@salimlko ,
@bansalpeeyush29 answer will make your video autoplay, and if you want to remove progress bar then remove "controls" attribute from video element( but, this will also not allow the respondent to pause the video) So your final code will be:
<video id='player' width="320" height="240" autoplay>
<source src="VIDEO_SRC" >
Your browser does not support the video tag.
</video>