Better Green Screen removal

He's demonstrating cleaning up the outlier pixels not quite covered by the Ultra Key effect. He doesn't take the time to explain this, but that is why he goes next to the Lumetri. It's another layer of keying out the green.

So he starts to get a quick & dirty key by just hitting the green button. Which selects a bit surrounding "green" with a small feather, and all luma and saturation values on the other two key scales.

Now remember, he's trying to get the last greenish pixels shifted to something better, right? So as his key is to clean up pretty much the 'blonde' wig thing, which is yellow, he's shading towards the yellow side as that is where there's a green/yellow tinge to the hair. 

He's checking the key while doing so. This is actually pretty fiddly work, and probably could take a few minutes to really nail. I've normally needed to work with the sat and luma controls at time to get a really solid, usable result.

But that's what he's doing. Using another tool to clean up a few more pixels. And at times, one can need to layer four or five separate set tools to completely get the clean signal for use. I've also worked with mulitple layers of the Track Matte effect to pull complex keys also. Which is another subject in and of itself.