How about create a webfolder
http://megui.org/meguirequirements that ~5 people have write access to, and occasionally upload new working builds there? It's not the "coolest" solution, but it's better than what we have now.
Since it's us doing the updating, that also means we can create our own naming convention. Something like
x264-2006-xx-xx.rar
mp4box-2006-xx-xx.rar
etc.
Then it's very easy for the MeGUI client to see what the latest version of everything is.