Hi there,
I don’t think it’s possible with current Wordpress MediaElementJS library (the video player). But maybe you can just disable the rewind of option so it will stop on the first frame of the video. Please add this to your global custom javascript.
jQuery('video').bind('ended', function () {
this.currentTime = 0;
} );
But since your first frame is black space, then when the video ends it will display black frame. Please change the value of currentTime to the frame you wish to display when it ends.
Please note that this is just a snippet which you can enhance or change, but we can’t provide further customization with that code.
Thanks!