This sweet, near-15 minute video comes from Tim Buys. This is what he says –
Gedinne, a charming little village at the borders of a nice paddock. On the edge of that pastoral paddock a beautiful road that climbs and descends, turning left and right, and which, forced by the logics of bending and sweeping in all kinds of directions, ends up where it first started. Which turns out to be very practical when you want to lap that road on your motorcycle. Lapping this road several consecutive times you end up having a race, a beautiful race, a hot race! As everybody wants the chequered flag first all ends up in the heat of the fight. And because of that heat they get thirsty, so some of them decide to mount a tent, put some tables and chairs in it, and a bar, of course.
Needless to say that those guys were Belgian adepts of classic racing motorcycles. So they founded a club they named CRMB (Classic Racing Motorcycles Belgium). An English name yes, because as good Belgians they thought it sounds better that way. The races are open to all pre-1972 motorcycles and you could take a one-off licence for this event.