The scariest part of that mythbusters episode was the UL pilot believed he wouldnt get off the ground.....
I find it amazing something so simple, can be made so difficult.
ignoring windsheer/microbursts/turbulence etc, evey aircraft flies in Nil wind, calm conditions, Ground speed is irrelevent.
the only time an aircraft is NOT in a nil wind calm condition is when its attached to something that stops it moving with the air mass. such as the ground...
even if the wind is 090 at 100 kts, the clouds wills till pass under the wing at the aircraft IAS..
not so hard.
and on the "oh geez, not this ****e again" downwind turn, again, only thing that matters is the path over the ground determined by windspeed relative to the ground.. once the aircraft is airborne, see above.. nil wind condition.. but the airmass relative to the ground is what will determine if you end up in the trees or not..