Later in the video when Jonathan begins placing edge loops for the subsurf, he places them in a way that they aren't overlapping with the original edges.
When I was following along, I made mine overlap because I thought the sharpening looked a little better. When it was time to add in some of the smaller details (and following into the next video), there were decisions made involving either only the holding loops or the original edges. I couldn't perform these steps because my holding loops were in the same spot as my originals.
If anyone else following along also made their holding edges overlap, it's easy to erase the bad loops and try again-- simply merge the vertices by distance!
