HLS seem to be the more popular format these days and browsers seem to start supporting it natively. I said hls/dash because both formats offers mostly the same

HLS seem to be the more popular format these days and browsers seem to start supporting it natively. I said hls/dash because both formats offers mostly the same benefit compared to just simply embedding mp4 files directly. You can use hls.js for hls and dash.js for dash, or video.js for both.