Great trick / easy reset / no slights required though recommended to buy special gaff substance ($5 on Amazon). Video instructions were clear. For $20 this is a good one you will use - especially for walk around

When I first learned the method for this, I thought, 'Oh, no. Another rough/smooth substance that will get dirty and leave ugly debris on the cards'. I was pleasantly surprised that the Sex Wax works well, doesn't get yucky and need cleaning and replacing as often as those sticks do, and it introduces (at least to me) the quick stick-and-release substance needed for this effect.
However, I'm offering this serendipitous occurrence to help others.
The link they showed on the tutorial for the wax they recommended was difficult to read. So, before I received the cards, I just went to Amazon and searched Sex Wax. Turns out there are approximately eight different ones, for different surfing situations (IKR?), all from the same manufacturer. Since I didn't know which one the mysterious link pointed to, I read about and considered them all.
I chose the one that made the most sense to me: i.e. Mr.Zogs Warm Water Surf Wax, Coconut scent. It goes on white and stays white for several practices. It seems to resist getting dirty especially if you're careful in handling the cards by not putting the gaffed sides down. If the Wax does get yucky, it rubs off easily. Be careful not to bend the cards when cleaning. Then reapply the wax. I use a little heavier application and further in from the ends than David instructs, but it works very well for me. The few changes in the routine card handling is a bit difficult to get right, but I kept at it, and it's learnable. BTW, no matter how much or where you apply the wax, it will be seen if you flash it. But it's white and with proper handling, it shouldn't be seen. The card they choose is examinable, but after many uses, the backs of these cards can pick up a bit of the wax, but it's minimal, and with a quick cleaning before an actual performance, it should go unnoticed.
Here's why I'm posting this lengthier than necessary review: because I bought the wax that made the most sense to me, after I got it and was pleased, I got curious about the type they recommended with that link. What if it was better?
A kind magi posted that he, too, found that tutorial link cryptic, and he spelled it out clearly in his comments. I manually typed it in, and ordered it. I tried it, and I prefer the alternative one. It came in a box which clearly identifies it, whereas their recommended wax arrived just wrapped in clear plastic - no box, no name, no text, no info. (Could have been just the one I was sent was boxless, etc.) It is harder wax than my preference, needs more pressure to apply it, and does not perform as well, IMHO. Basically, it's harder enough that it doesn't stick as easily, separates too easily, and is harder to rub off to clean and replace.
I won't even try to give you the Amazon link to my preference. Order carefully by the name I gave, and I believe you'll like it better.
Extra Sensory Prediction is a great effect and pleasantly different from the typical ones with typical cards.
Note: those 'sticks' are fine when you're in a pinch or need a quick touch up on a card or two.

This is a great effect—quick, easy to perform, with a great kicker ending. The quality of the props is excellent, and the tutorial goes over how to maintain them should that be necessary. The tutorial also contains a thorough explanation of the principle behind the trick and the construction of the gimmicks, so you could no doubt work out other applications using business or wedding names, etc. A typical, high-quality, Jonathan/Mavresis effect.

This will be my new prediction trick for walk around magic. I like it because it's not a multiple out. Works great & has a easy reset