They have done the Grammys in the past. Other than the general excitement of attending such an event, there are also three ways a seat-filler can get lucky. And three, if they're really lucky, the person whose seat they're holding may not show up at all, letting them keep the seat for the entire show. So getting in free as a seat-filler, even if it is a game of musical chairs, could be considered a bargain. However, there are some downsides, as well.
Waits can be long, in small back rooms.
They don't guarantee that you'll get a seat. And they don't pay you. You have to provide your own transportation and meet their dress code for each event. And you can't ask stars for autographs or take photos at the events. Also, they encourage you to go to their smaller events to improve your chances of being selected to go to the big events.