One of our dogs watches TV for very short periods, like max 2 or 3 minutes, and only if there are animals on screen, preferably with sound. He definitely sees the pictures and follows the action. Knowing his personality I figure he doesn't care about them once he sees their pattern of behaviour doesn't bring them into the house or yard. Also he sniffs the air but can't pick up a scent of course; that seems to be the final bit of interest before he goes back to whatever he was doing--sleeping or wrestling or playing Ginger-ball or whatever. He was more reactive to that stuff when he was a puppy and young adult dog.

The other two dogs, ages 6 and 7 yrs, don't seem to see the picture at all and never did. On rare occasions their attention is attracted by animal sounds on TV they figure out pretty quickly it's not connected with any living thing in the house, yard or anywhere else they go, and they immediately (a couple of seconds tops) return to whatever they were doing.