found the answer: ''Firefox does not support the MPEG H.264 (mp4) format at this time, due to a philosophical disagreement with the closed-source nature of the format.'' Updated Nov. 8, 2013 ''Network infrastructure giant Cisco has announced plans to open-source an implementation of the H.264 codec.... read more: http://stackoverflow.com/questions/12878068/video-format-or-mime-type-is-not-supported'' other: https://blog.mozilla.org/blog/2013/10/30/video-interoperability-on-the-web-gets-a-boost-from-ciscos-h-264-codec/ its 1 year after but Mozilla still not implement HLS video.