We get our support for that from the application “gstreamer-0_10-plugins-ffmpeg - GStreamer Streaming-Media FFmpeg Plug-In”. You should confirm this is loaded for openSUSE 13.1. if you use that version, which I am not sure you mentioned. For multimedia support here are the guides:
As far as I know, openSUSE does not provide direct support for Firefox addins, but you must install the required codes which is the purpose of the two blogs you need to use. Good luck.