Looking for card trick explanation.

[ExRayTed]

Years ago, a friend performed a card trick on me.I've since lost contact with him but am dying to know how it was done.

He took a standard deck of cards.He may have prepared the deck beforehand..not sure.He shuffled them with a basic overhand shuffle.He then got me to hold the deck and place cards face down in 2 lines,one that I thought would be black and the other red.Whilst doing this he got me to stop and see how I was doing by turning over the last card I'd laid down (about halfway through I suppose).It was wrong so he moved it into the correct pile.

I continued placing the cards face down in either the red or black lines.When I'd finished,he turned all the cards over and they were all correctly predicted..one line completely black and one red.

How?!?! My weak google-fu skillz have turned up nothing.Help me please

 

[ExRayTed]

Revealing magic secrets is BAD!

However, I could perform that magic effect for you if you wish.

I know it's bad.It just impressed me so much.I've now found out the name of the trick (thanks to the link above) and even though I've watched how to do it,it still impresses the hell out of me.I love close up magic of this type and have watched some user videos on these forums (perhaps they were yours? I think they were..sleight of hand coin stuff maybe?) The dedication and practice needed to perform some of this stuff whilst making it look easy is very impressive.

Thanks for the info anyway