Hi Kent. At the 4 Minute Mark, when you said that you were trying to "Split" the head in half... I had some difficulty selecting all the edges that ran along the back of the head.
Did you turn off Limit Selection to Visible?
https://www.google.com/imgres?imgurl=http%3A%2F%2Fwiki.blender.org%2Fuploads%2Fb%2Fbe%2F25-Manual-Modeling-Meshes-Selection-mode-buttons.png&imgrefurl=http%3A%2F%2Fblenderartists.org%2Fforum%2Farchive%2Findex.php%2Ft-239216.html%3Fs%3Ddc539da3560f7171130b1e708ec6fcaa&docid=VYvSKhw5clLoyM&tbnid=gdfHniRWA61gsM%3A&w=190&h=141&bih=1031&biw=1600&ved=0ahUKEwi7wc7VvffNAhULwGMKHT0IB7kQMwgfKAEwAQ&iact=mrc&uact=8
Judging from your question above this is what you are looking for.
I believe Mr. Trammell is using (ctrl click) to select the edges while in edge mode utilizing Pick Shortest Path.
