That looks like a problem with GStreamer. Make sure that you have the latest GStreamer updates.

You can try to disable GStreamer by toggling media.gstreamer.enabled to false on the about:config page.

roghibau said

bp-28904306-79cd-4947-aee0-48ee02150719 19/07/2015 20:48 bp-02ed0492-9b0b-4c1c-9000-387de2150717 17/07/2015 17:22 bp-536d80e0-6734-40cc-b5d9-724a22150717 17/07/2015 17:20 bp-b9fe2914-8f61-4864-8a3b-6cbb02150713 13/07/2015 20:54 bp-034177ac-3189-4bd3-a144-dda1f2150711 11/07/2015 17:20

Resolved a lot of graces