Most slot/poker machines take notes or TITOs (ticket-in, ticket-out). They did it only because this was their grand opening year - casinos do not run this type of promo very often // If you lose $100 in a single day, they will load $100 in freeplay on your club card. Sometimes a casino will run a promotion - Cosmopolitan has the 'lose $100 on us' promo. The bigger freeplay amounts are almost always a promotion the casinos send out to players who gamble a nice bit of money in their casino.
Usually, it gets loaded onto your club card and you can access it at a slot machine (after you've entered your PIN). Some casinos give you a little freeplay (say $5-10) for signing up with their players club card.
