my understanding is that you will only get a refund if the game is canceled entirely. if it is postponed, and you are unable to attend on the new date, you are SOL. i've been considering getting away tickets to our first game in KC, but i'm not sure what happens if i buy the ticket from an individual seller and the game gets canceled. to my knowledge, i'd lose my money - otherwise who would i get my refund from? would love to hear otherwise though!
edit: FYI, this is on stubhub: "The NFL lockout isn't settled The NFL is currently in a labor dispute with its players. If the lockout is not resolved by the start of the season, August 1, here is what you should know.
Due to the NFL lockout, there is no guarantee your favorite players will be in the game. If you buy tickets and the game is played, the tickets are yours to use, regardless of who is playing and if the game is rescheduled. If the game is cancelled, we will refund the cost of the tickets plus service and delivery fees."