Walter works at a carpet store which is located next to a bank where people have tunnelled through to the vault and ripped off the cash. He is obviously a "valued employee" because he and three others set up a scam where the cops and Five-O follow a truck which they think has the money, but it doesn't have it. These four then attempt to flee with the cash, but they are stymied by the cops and Five-O who are wise to their scheme. In addition to the sequences here, Walter, who is wearing a blue shirt, can also be seen working in the carpet store's warehouse earlier in the show (still shot below).
Click on the arrow in the video below to watch it.