Probably not. The idea was to encourage "nobodies" to create math teaching material. People who thought they might want to do that, but never got started.
The exposition contest was designed to give them a little push and get eyeballs on their content, so they've got an actual chance to be noticed, no matter if they win.
An established YouTuber entering it would have taken attention away from those new people.
Per the contest announcement [0], the intent was "[...] to encourage people who've never put stuff online before" and "[...] to offer a little bit of activation energy to anyone who has thought about doing something like this, but just never got around to it".
So the spirit of the contest excludes those YouTubers.
Probably "The Beauty of Bézier Curves" [1], one of the choices by 3B1B, comes closest. It is already a relatively large channel although usually focused on game dev tutorials rather than math explanations. This video bridges those two areas and is absolutely beautiful.
Interesting--I recognized that animation style immediately, because she's also the creator of a Unity asset library called Shapes[1], (a "...real-time vector graphics library with high-quality line drawing and infinite resolution shapes, rendered with advanced anti-aliasing techniques"),
which seems to have been used to create the video.
