Built in and simple solution
Video media type display
Admin > structure > media > video > display
Under display set multiple videos to a single html tag
Set the video field to allow 2 videos to be uploaded
Admin > structure > media > video > field settings
Upload 2 videos
I've got 2 versions in the video tag
It looks like you have a typo in your breakpoints.yml. See this the breakpoints.yml documentation.
An example as defined in bartik theme:
mediaQuery: 'all and (min-width: 560px) and (max-width: 850px)'
The correct key is mediaQuery, not mediaquery. The result is your media queries aren't recognized ...