Yeah, It's sad. Walmart has pressured all retail chains to be more competitive, thus they resort to hiring any a-hole off the street because pay, and availible sucks too much too keep the good employees around very long.
Though being in retail for a while, I have had few customers that were complete dicks. It's very hard keeping your cool with those types, you just feel like snapping.
If I were you, I would say, oh i see, you rather me buy this blu-ray somewhere else then. then leave.