I will direct your attention to her fingers, which aren't much narrower than the dick. Here's their RedGifs account
$un 0f $am's Porn Gifs | RedGIFs
It's kind of an odd one because some of the vids when it's compared to her head or blowjobs are quite convincing, but it's not much wider than her fingers and she never has to open her mouth wide. I think she'd just very small and his dick's really narrow so in combination it looks huge but is probably above average length, below average width.
You can see his fat pad is stretched along the direction of dick in some vids too, so there's some frame stretching going on too.