Yes it is. That is what they make their money off of, the difference between what they earn off of the labor of the video creators and the money they pay out. If nobody uploaded videos, youtube could not sell attention just like if no steelworkers arrived, the steel mill can not sell steel. That applies to all social media/user generated content platforms.
Now, you might argue that this does not feel like labor because it's more voluntary than labor usually is. Which is totally correct and exactly why this industry is so lucrative.
Not sure why you were downvoted but you're right. YouTube, in a total inversion of the TV business model, doesn't pay creators for anything until after it's been monetized -- and then they take a cut first. The cut is so early in the process that millions of videos are monetized and the creators are not even aware, much less paid.
This is the reverse of the Hollywood TV model where you paid creators first and then tried to monetize the content you owned. It's certainly still labor to create it. The only things that have changed are the ownership, licensing, and payment stream.
Youtube creators can take their content elsewhere, at any time I believe. Traditional TV studios have longer term contracts and there are often more folks involved than lone YouTubers and their patrons.
They can take their content, but not their audience, making the whole thing rather useless. The only thing that enables that in film is the relative neutrality of cinemas and streaming platforms.
I don't think recognizing it as labor needs to change how you feel about doing it at all. I'm doing labor that makes HN more monetarily valuable right now by writing replies and I'm obviously fine with that. And as to almost everything being labor in some way... well, that's the world we live in for better or worse.
Now, you might argue that this does not feel like labor because it's more voluntary than labor usually is. Which is totally correct and exactly why this industry is so lucrative.