I normally send video using Icecast2 with Ogg/Theora video and VideoLAN. I can use a playlist or screen device as a source. But I'm not sure how well libogg, libtheora, vlc, and icecast2 on IRIX is these days. I understand you may have a limit and need MPEG4, but for other uses, it's almost invaluable how efficient the setup is.