Firefox supports H.264 via system codecs, and supports MPEG-DASH as of version 41 (currently beta, will be stable in a few weeks). MPEG-DASH is a more open standard, and has better support for adaptive bitrate streaming, so I think it&#x27;s likely to become the defacto standard in the future. It&#x27;s fairly new so isn&#x27;t supported everywhere yet, but it&#x27;s getting there, and seems to have a lot more industry support than other options.