header video on youtube doesn’t work on mobile

My header video is pointed to a very large video on youtube.  It works great on a PC, but the video does not play on mobile device.  Any way to fix that?  The documentation says there is a 8MB limit of video uploads (!), which is extremely limiting.  There also does not appear to be a way to point to a self-hosted mp4 file on my webpage's server.  Any ideas?  Thanks!