I noticed that there a few variants of the Mega Man thumbnail missing from its category page, both of them being in-video ones, so perhaps we can add these to that page:
"Fire Man Stage": Notice how this one is a shade darker and more wider than the original GiIvaSunner version. Not sure if this counts, though.
"Game Over" and "Guts Man Stage (OST Version)": This version of the thumbnail doesn't have the copyright notices at the bottom of the screen, and is zoomed in.
There is also one missing for Street Fighter II: The World Warrior that is used for the "Chun-Li's Theme" and "Ken's Theme (Beta Mix)" rips, again seen in-video.