Seth and Scott Avett spend a good chunk of their lives on one tour bus or another, so asking them to perform in one isn't all that different from asking them to perform in one of their own living rooms. They may be far away from their native North Carolina — to be exact, they're captured here in a Camden, N.J., parking lot in conjunction with the XPoNential Music Festival — but the setting is cozy enough for Seth Avett to brew tea before performing.