I was kinda waiting for a doe to appear. Never saw anything wobble, altho I did see your right grip vibrate some. Why do you blip your throttle with the clutch pulled in just after you go "WFO?"

Try this again, only let go of your bars at 60mph. See if they begin to oscillate about 47mph and straighten out by about 35mph.

 

On the FL series Harleys, pre-2008, the frame design was such that the swing arm bushings were able to flex at speed in a high speed corner like a sweeper. It was very evident at 80 to 90 mph on a highway curve. I experienced it several times on a 2004 Road King Classic. There were aftermarket stiffening plates you could install on the bottom of the engine that tied to the swing arm to eliminate the issue. When HD re-designed the frames in the 2008 model year, the issue was eliminated in the FL series bikes.