I love this effect. Have the spectator choose a card and sign it if you wish. Then the card is "lost in the deck" before the magician spreads them all over the floor (or in a ribbon spread if you prefer the neat look). The magician passes his hand over the deck and one card begins to move. When it's collected and turned over, it's the signed card. Thinking invisible thread? Think again. This effect can be performed with the cards poured into a sealed Zip-loc bag and it will still work. And they get to keep their signed card to examine forever...because they'll never find anything wrong with it since it's just a normal, signed card.
While I like the handling Jeremy uses for the gimmick, you'll probably come up with the same idea I did when you watch the video. There's something else you might already own if you're into PK magic that will do the same thing and allow this trick to be almost completely impromptu (provided the right color deck is being used and you have your gimmick on you).
For a wonderfully spooky effect that will blow your spectator's minds, this is great. And you end fairly clean with the ability to repeat the effect immediately if you so desire.