Dear, I think that what you propose does not have syntax errors, at most the definition of the class "video" is stuck with the definition of the src attribute, but nothing that affects the operation of the tag.
As you can see in the following excerpt, I am using your same HTML structure (ignore the link tag, it is only for importing Bootstrap 4), with the only difference that in the src I defined the path to a video valid for the player .
<link href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" rel="stylesheet"/>
<div class="embed-responsive embed-responsive-16by9">
<video class="video"src="https://www.sample-videos.com/video/mp4/720/big_buck_bunny_720p_20mb.mp4" autoplay loop/>
</div>
Do what Tegito123 suggests:
[...] first of all you should see the compatibility of the different video formats for each browser, apart from that your source or url of the video is well defined [...]