Hi Jean-Pascal, in theory this could be possible but in practice it will be very difficult to implement. You’ll need to integrate both the light box and the video player into your theme manually, without plugins.
Also, you need a video player API. For example, if using the Youtube player (embedding Youtube videos) you can read how the player API should be implemented on https://developers.google.com/youtube/iframe_api_reference … as you can see, not easy. And once done correctly, you’d not even be ready.
You’d then need to make the light box script talk to the api on its close action. Relatively easy but still, not possible with the plugin. Only when integrating the light box manually.