At 5:35 after deselecting the root verts, I scale down, the highlighted verts just move downward. I'm using 2.90. I've deleted the legs and started over but still same. Any suggestions?

How do you scale? With the Skin Modifier, you must use CTRL+A to scale the segments.

spikeyxxx. You. Are. Awesome.!     Thanks so much. Usually I can figure out bumps in the road with Blender but just couldn't find the answer to this one. I was using normal Scale and then tried ALT-S. Never thought about using CTRL-A.  I must remember, Use CTRL-A with the skin modifier. Happy Blending !