Hey there! At this point in the video I am using the "Mask" brush to mask off areas that I do not want to affect with my sculpting. You will be able to find that brush in the sculpting mode, mixed in with the other brushes. As well, I was able to change the colour of the hat's display in the shading panel, located at the top right of your viewport, to the right of the 4 material balls. -Chunck :)
