In your test image the lines for the bottom triangle are straight. The lines continue upwards to form a rhombus from the tips of the "wings," whereas in the video they come straight across until they form a lip underneath where the main engines would be.
At this point some of the "experts" I'm sure have already crafted replies calling me a stubborn a__hole and an idiot, but here's an important question: Is it possible that the shape of the aperture, being similar in shape to the shuttle from behind, caused some sort of magnification and sharpening affect?
You should try my experiment with your own camcorder then you'll understand why I completely reject the chance that this was the shuttle. By manually adjusting the zoom, focus, and exposure on my camcorder, I could make all sorts of different shapes, make the dividing line between light/dark move up and down, etc.
Before I did my experiment, I found a 3d model of the space shuttle on the web and created an image of it from beneath and behind in POVRay. One thing I noticed was that the shuttle, from this angle, is almost all dark. Another thing is that the "OMS pods" are way too far apart, too far apart to be explained by motion blur, etc.
At this point some of the "experts" I'm sure have already crafted replies calling me a stubborn a__hole and an idiot, but here's an important question: Is it possible that the shape of the aperture, being similar in shape to the shuttle from behind, caused some sort of magnification and sharpening affect?
You're not an idiot. To photography laymen (eg. me and you), the image looks like a view of the space shuttle at a particular orientation. Those who poured derision on our initial interpretation without explaining why are the idiots. I'll make sure to pour derision on them when they venture into my field of expertise in the future. FreedomCalls really went the extra mile in explaining what was going on and I appreciate it.
There is a way to settle this scientifically but it would involve getting data on a typical camcorder lens and shuttle dimensions. A shuttle has a wingspan of around 80ft and the Columbia was about 200,000ft away. I'd like to see one of the dismissive "experts" use this and the typical camcorder specs to show how much of a zoom was necessary to get an actual image of the shuttle.