This seems the most ridiculous - internet of shit - thing; when in the video he turns the "Vessyl" and it reads beer ... just look at your can, it's written here.
Tracking liquid calories is easy, you drink your soda can and the number of kcal is indicated clearly. You drink water from the tap and ... you consume 0 kcal.
If you are like me and drink a lot of water each day, you will get really really tired of measuring it and keeping track of it. Making it automatic is important - it eliminates the psychological component of trying to beat your numbers. A product like this is not just about tracking calories but also how much you are drinking.
Very few people have any need to closely track their water consumption unless they have a particular condition, though, and this product seems to be marketed to a fitness/lifestyle market, not health care.
