Apologies for overlooking your post. I have a sense that you have not switched off the eyeball for this gray solid.
I’ve not done this tutorial but I’m quite certain that the grayscale layer/precomp is used as a displacement map. If so, it’s visibility should be switched off.
If all this is true, then it is advisable that you look into working with a more structured learning experience with AE. It will be more rewarding in the long-run.
Take a look at the Meyer’s books for a comprehensive, yet inexpensive option towards learning AE. That’s where most of us started and many of us are still hooked on their books.
Cheers
Roland Kahlenberg
https://www.broadcastGEMs.com – Adobe After Effects project files
https://www.myspace.com/rorkrgbspace