I get the jist of the issue and why it appeared now. Looking back at the video, I'd say change line 714 from:
return '<video width="100%" controls ><source src="' + str + '" type=video/' + temp.slice(1) + '></video>';
To:
return '<video width="auto" style="max-width:100%;" controls ><source src="' + str + '" type=video/' + temp.slice(1) + '></video>';
The only thing I can think that the width was attempting to be 100% was to keep text or other images from floating to the right of the video.