I like using Coleman (crappy) Utility Cord. It is similar to the gutted paracord suggested by hppyfngy and has just the right amount of stretch to get nice and tight. I use 7-8 wraps.
Another hint...using the whipping method you show (my favorite), don't cut the ends off when you're done. That way you can easily pull the whipping back apart and reuse the same cord as many times as you like.