Background bottom margin suddenly changed

I was really loving this plugin. But something changed. I don’t understand why the background bottom margin (surrounding all video) suddenly changed, on its own, to show a lot of empty space underneath the video. The background bottom margin used to be equal to the top margin. How can I get it back to where it was?
http://www.supseniorenthusiasts.com/SUPguide/sup-fitness/

https://ww.wp.xz.cn/plugins/gallery-video/