I installed automatix to enable video playback on firefox. However, after I issue the command automatix I get the following:

/usr/bin/automatix: line 49: lsb_release: command not found
/usr/bin/automatix: line 51: lsb_release: command not found
/usr/bin/automatix: line 53: lsb_release: command not found
/usr/bin/automatix: line 55: lsb_release: command not found
/usr/bin/automatix: line 58: lsb_release: command not found

Is there any way I can make the automatix work on Mepis 3.4.3 or at least install a video player and quicktime on my firefox browser?

Unless their's a mepis version, I highly doubt it (and if you're using an older install that isn't based on the Ubutu base, you simply can't).

You problem is easy to solve without it though.
Just install mplayer and it's mozilla plugin.
If you miss some codecs, take the "all" package from the MPLayer site and place them in "/usr/local/lib/codecs/" (create it if it doesn't exist).

I visited the Automatix website and they posted a rep for the Mepis users. However, after updating my rep list and installed automatix, I got that error. I've installed mplayer, now how about mozilla plugin?