On their demo page
demo.joomlaworks.gr/allvideos The two MP4 video examples end the way you want. But you're right I don't see any way to specify that happening. I've loaded it on a demo site and see what I can see a way.
They have custom options, and there may be one for this, but I can't find it.
Custom options per video
Easy, descriptive syntax for media embedding. Use: {format/provider}filenameORvideoID{/format/provider}
You can also use syntax like: {format/provider}filenameORvideoID|width|height|autoplay{/format/provider}
...where "width" and "height" are the media dimensions in pixels and "autoplay" is enabled using 1 (use 0 to disable it).
For example, a YouTube video with 600x450 dimensions that autoplays on page load would be displayed adding this plugin tag in your Joomla! article (or K2 item, or Virtuemart product etc.): {youtube}he73js822|600|450|1{/youtube}
Have you asked JW about this? It's in the demo, but don't see it in the docs.
Let me know if you've contacted them and they have any answers. In the meantime I'll try to see if I can figure it out.
Ed