This video seems to be controversial amongst the comic book crowd because (as the title says) Ghost Rider "pwns" Galactus.
They say that there should be no way that the penance stare should work on Galactus; he's "too big" to feel guilt blah blah whatever.
Me, I've always interpreted the penance stare as inflicting pain proportionate to the evils its victims have committed. Galactus might find planets without sapient life less satisfying, but he could still preferentially go after them; instead, he seems to preferentially go after inhabited worlds. When you eat planets on a more-often-than-yearly basis, that choice in cuisine is pretty darned evil.
I find it perfectly legitimate-it's like Ghost Rider is the paper to Galactus's figurative rock. Just because Galactus has a big, heavily armored (once again, figuratively speaking) mind doesn't mean he can shrug off a demon-powered guy who specializes in that kind of punch, especially since he's pretty badly weakened in this scene (he's both hungry and recovering from food poisoning).
Not to mention it's satisfying seeing the big goof take one to the chin like that.