Regarding the darting and hovering comment...
It was to explain a poster questioning the technology that allowed an aircraft...or any machine for that matter...to make sudden drastic changes of direction at high speeds with no negative effects on the structure or possible crew.
If they were a lifeform itself...the mobile ability would explain a lot, IMO.
There’s evidently some inertial dampening effects vis vis the gravity related propulsion etc.
I’ve seen various explanations for it but they mostly seem to boil down to some variation of the above.
Interestingly, for longer trips, some humans have been encased in fluid filled chambers . . . IIRC, one even having to breathe a highly oxygenated fluid in the fluid filled chamber—very disconcerting.
And, many of the ET’s are quite light—low density critters.