Small Objects Levitation
This appeared to be totally impromptu which made it even more impressive. This type of levitation is performed by using "invisible thread" which can either be purchased as a proprietary brand from good magic suppliers or by separating some fine polyester thread into individual strands and using a single strand.
One end of this strand should be attached to some sticky tape and placed high up on the magicians body such as a shirt button.
The other end can be placed at the right moment to a solid object ( In David Blaine's case, the tree.)
The magician then stands at the correct distance so that the string is tight and the object ( a bill or a leaf ) wrapped around the thread which is above the magicians hand. This should look like the magician is just scrunching up the note in the palm of their hand.
By using very small movements of the head or body, the magician can then tighten the thread causing the note to rise and is also able to move his hands around the object to show that it really is levitating.
The object can then be made to return to the palm and be examined by the spectator. The magician can then casually walk away, the thread breaking which is not a problem as it is reasonably priced. This trick is also performed more smoothly and discretely by use of an Invisible Thread Reel which is used by professional magicians and which can be ordered from most good magic shops.