Given the angular size presented, if it was 100Km from the observer, it would have been under 3m in diameter. The moon was 36 degrees elevation at the time that the imaging started, so an object such as a balloon ~40Km in altitude would have been 70Km away. That gives us an object size of <2m if we assume <40Km altitude.
A bat or bird a few Km away would have the right angular size, and would account for the movement pattern. A balloon at altitude would be less likely to shift direction. An alien spacecraft would probably have somewhere to go and not be wandering back and forth
Alas, it is all just speculation.