This is the trick that was performed on one of the David Blaine specials. The same trick as you'd pay $29.95 for on a DVD currently available from online magic retailers.
EFFECT
The performer takes a spool of thread, unravels about a foot of it, and then breaks if off, putting the remaining spool aside. The performer then proceeds to break the thread into 6 or 7 clearly broken and individual pieces.
Then, holding one piece in one hand, the other pieces are rolled up into a ball and "squashed" onto the piece held in the other hand.
When this is unraveled, it is seen to be, and is, completely restored to its original length.
