for a BM3.5 and above, what is the recommended software for realizing
at least outbound, or even maybe inbound video or shared desktop

The postings I read here about netmeeting seem to tell in short, that
it is an ugly thing, opening of (many, may be all) UDP ports is
required and h.323 isn't capable to funktion with BMs NAT

So maybe a totally different approach might be the solution? Something
like a Gateway, that is NATed through the BM to a public IP, and the
local LAN's clients connect through this gateway to external machines?

Any suggestions welcome,