The German company that posted this video, offers several solutions to the dilemma thru the tanks they fabricate.
One of those is to wrap the clunk with some absorbing pad, able to retain enough fuel for short times as to avoid air entering the tube.

It may help in this discussion to consider that the engine sucks small volume of fuel, and that it can be alive for several seconds only with the volume contained within the pick up tube, hose and filter.

A 0.40 engine can fly a model for 15 minutes with less than 8 ounces of fuel at full to medium throttle.
As 15 minutes are 900 seconds, the average fuel usage is 8/900 = 0.0089 ounces / second = 0.26 cc / second.
At idle, it must be much less than that.

Also, I have seen that any middle size bubble, pass thru the spray bar fast enough (due to its low density and friction) as not to kill the engine, if there is enough vacuum in the carburetor ventury (high rpms).

One main cause of flame out during static nose down or inverted flight, is build up of fuel in the crankcase by enrichment of the mix due to gravity.
During a dive in, the flow of air forces the propeller to turn, regardless of the right mix entering the engine.
I have never had a dead stick during a dive in, but many during inverted flight, when the propeller is loaded and the right mix is critical.