Go on, finish the video. You need to~
Aw, isn't he nice? He seems like a very likable person, charming, and very charismatic. He'd make a perfect insurance salesman.
So, what we've just seen in the video was that the water apparently disappears. To the common, untrained person, this magic trick is almost impossible to crack. However, we have the power of science on our side.
The key ingredient in this trick are chemicals known as Super absorbent polymers. These cross-linked acrylic polymers are referred to as "Super Absorbents" and "Water Crystals", and are used in baby diapers. From our findings, we can infer that the magician laced his cup with super absorbent crystals, and naturally, due to its ability to hold lots of water (sodium polyacrylate holds 800+ml of water per gram!) the water apparently disappears.
Sodium Polyacrylate can be extracted from baby diapers, or purchased from your local garden store. You might need a few extra cups though.
Also, magically, the reaction can be reversed with a few spoons of sodium chloride.