Yeh that's BitzaWood.

They're threaded inserts. You just pilot an 8mm hole, crank in with an Alen Key, et voila! Instant M5 thread to bolt to.

I got the idea from the Gimson drive units, except those require a press since the inserts go into Nylon.

Shame about not making it, I've been nagging RoboChallenge about hosting an event August/September time so in the middle of the year, but I think some of the UK guys are going over to Mad Metal Machines in Germany in September since they run a Full-Combat FW event.