[SunkenCiv]

There’s nothing remarkable in the still image, here’s the largest of the YT stills:

http://i1.ytimg.com/vi/sSz3DKZPM38/maxresdefault.jpg

There’s a lot of transient events, light and dark, in images made by orbiting telescopes and cameras, to the point that it took decades for Louis Frank’s “small comets” to be accepted to any degree, and not just dismissed with a hand wave:

http://smallcomets.physics.uiowa.edu/blackspot.html

My wild guess is, the reason the DoD brought him into the loop in the first place is, they suspected the same thing, but needed someone with expertise to “discover” them and figure out a way to differentiate them from hostile ICBMs.

[Yosemitest]

"... nothing remarkable in the still image ..."

I disagreee.
One moment the image is there for a few photos and appearing to hold its position against the solar winds,
and then the next moment it disappears, but comes back later, and in the same position it was in in the first p;lace, yet appears to be translucent or almost clear.

"... Louis Frank’s “small comets” to be accepted ..."

There's a big difference in "upper atmosphere" observations against a planet, versus "inter-solar-system space" observations with no atmosphere.
"Water vapor" might be translucent or almost clear in space, but I would assume the space pressure (or lack there of) and solar winds would NOT allow it to clump together to any size at all, but would quickly blow it apart into microscopic particles.
But that's just my educated guess.

I enjoyed reading The Original Discovery, but to me it's only a theory, worth some thought, but not to be accepted as fact.
No, the heat from the sun's reflection ~ reflecting off of the inside of "STEREO (Solar TErrestrial RElations Observatory) Heliospheric Imager (HI)" "glare shield" ~ makes more sense to me.
It explains the reason the observed item "appears and disappears" in and out of the same spot, at random.
But that's just my theory.