Use Fallback Urls with HLS and Dash

You can combine the last three best practices together to serve an H.265 HLS file, then a WebM Dash file, then a h.264 HLS, and even a fragmented MP4 for browsers that don’t support any of these (IE11 on Windows 7 or earlier).

Current Elm Difficult = Very Hard

If your browser supports HLS natively, you can just do some fallback Urls, but if you have to use the HLS.js or Dash.js plugins, it means a whole bunch of complicated roundtrips through ports to figure out how to support these files.

A better strategy might be to test for HLS.js and Dash.js support and send that info through flags, but that means downloading HLS.Js and Dash.js from the servers before you need them, which isn't great.