hehe marc.
must admit, i didn't read your link. I thought it might've been a link to the redo (?) guide.
if vdub won't open an avi, then you don't have the proper codec installed. i work with mpeg4 constantly. Virtualdub is rarely NOT on my screen. (albeit minimised and crunching away)
install the codec! (and use gspot to find out exactly what codec you need!)