In Manage display, these modules add a new Format called HTML5 Video Player. In configuration options, it is mandatory to set a width and a height in pixels. These values are then used in the HTML element video :
<video style="width:550px;height:310px;"> <source src="path/to/video.webm"> </source> </video>
So it is not responsive at all… I would rather style the width and height through CSS, with something like max-width=100%; but as it is mandatory to put width and height values directly in HTML, this just won’t work.