Here's (hopefully) a clearer how-to for the magical unknown wrap:
First make a loop and lay it down the entire length of your wrap, leaving extra loop on one end (left side of pic) and extra loose string to pull on later at the other end (right side of pic):
Begin wrapping at the loose-string end and ending at the loop end:
When you get to the end of your wrap, slide the end of the string you've been wrapping (the end on the left side in the pic) through the loop you left sticking out (at the left):
Pull the string at the beginning of the wrap (right side of pic) to tighten loop:
Then pull the loop string (on the right) another half the length of your grip to put the "knot" in the middle of the wrap (between the wrap and the material you're wrapping):
Then trim your two loose ends even with the wrap and you're done :)