Video display in mobile

I’m using the ‘Responsive’ WordPress theme because it’s a good mobile theme. My videos look fine on a desktop, but in a mobile the the video is wider than the page background and it looks bad. I tried support at the Responsive forum, but they referred me to this forum. Any ideas on how to make the pages with videos conform better for phones?

Example: https://50.6.236.253/video-clips, https://50.6.236.253/video-clips/featured-video

Thank you.

https://www.ads-software.com/extend/plugins/player/