opensuse is patent free, for legal reasons patented codecs are hosted on packman
you need codecs from packman for full multimedia support
Firefox will play mp4 files using ffmpeg as a backend
Firefox it self does not do the decoding
on linux the decoding is done by libav (ffmpeg’s library part)
on windows vista and above it uses microsoft’s windows media foundation
as XP has no mp4 (h264+aac) support Firefox will not decode mp4 on XP only
to get your fox working tell us your repo list
zypper lr -d