Header video sizing

I uploaded a video and saw how far down it went, It takes up way to much room! I created a new video that was 1920x700 so it was wide and short but then the theme stretches the video to fit and makes it look aweful. Also when I shrink the video in preview it shows that it just cuts the sided of the video off in phone mode which again is not good. I then checked on my phone and it still just shows the picture that I had, no video. That may be a cache thing, idk. But is there a way to have my video show the size I create it and shrink when it's on a phone so it still shows the whole video as it should? There aren't any options in the theme setting for sizing which is strange.