The scotchloks are a lot like some of the replacement lamp plugs that are out there. You cut the wire straight, push it into the plug, when squeeze the prongs together. Teeth on the prongs pierce the wire and make the connection. Supposedly. I've never been very comfortable with that kind of plug because it forces a lot of current through a very small contact area, and that concerns me. I'll stick with screw terminal plugs.
Speaking of which, I need to remember to get a replacement plug. The molded on plug on my long extension cord is letting loose.