Hot The reason I asked is... The video didn't show the engineman , opening any valves or taps. He went through the reverse/ forward procedure and I thought maybe someone on the ground had opened something..
Actually, if you watch carefully the Engineer's hand DOES go to the steam supply valve for the cylinder cocks, located on the back-head, to make sure that the cylinder cocks are STILL open. The UP preferred the steam operated brand of cylinder cocks, i.e. they require boiler steam pressure to CLOSE the cocks. If there is no steam, then the cocks are normally open, and the locomotive can be easily towed around the shop area dead. The other REALLY BIG ADVANTAGE of the steam operated cocks is, if moisture/condensation does continue to accumulate in the cylinders, even after being blown out, the force of the hydraulic pressure of the water becomes greater than the steam pressure holding the cock/cocks closed, and the cock quickly "spits out" the water and does no damage to any machinery.
For what it's worth, the "other brand" of cylinder cocks is air operated and are normally closed, requiring air pressure to OPEN the cock. Thus, if there is no air pressure, the cocks are normally closed, and the locomotive should NOT be moved until air pressure is supplied to open the cocks.