Adding subtitles to video file

[Rodolfo Medina <rodolfo.medina@gmail.com>]

Hi to all Debian users.

I installed `subtitleeditor' in my Lenny system in order to add comments to a
certain video file but, when I try to open that file from within
subtitleeditor, the following error message appears:


GStreamer plugins missing.

The playback of this movie requires the following decoders which
are not installed: 

MPEG-1 System Stream demuxer


Can anybody please suggest the proper package(s) required so to work that out?
I tried installing gstreamer-tools and gstreamer0.10-plugins-bad, useless both.

Thanks for any help
Rodolfo