Marla was sitting next to me as I was watching something on Animal Planet on a 42" full HD screen, when a mouse came on the screen. She perked up and leaned towards the screen. Suddenly a large snake jumps out, snaps up the mouse and swallows it whole. I thought that poor cat was going to have a heart attack-she actually hissed/screamed at the screen in anger and fear.
Well, I don’t know about WATCHING TV, but Norma Bates Kitteh definitely HEARS cats in videos…
Today is the first episode of the annual Kitten Bowl. One of my cats (the smart one) is glued to the TV, right up close, taking a break only for commercials. The other cat can’t be bothered.
But, but . . . the commercials are the best part!
Can a Cat Watch TV?
Ahem. MAY a cat please watch TV?
One of my cats spent a couple minutes once watching a follow-the-bouncing-ball singalong and trying to catch the ball.
See, that’s what’s hard about it. You have to convince the cat. 
I also had one of those, with one of those big TVs that doubled as furniture. Believe me, I got more feline help than I wanted when playing Space Invaders or Breakout.
I’ve seen cats apparently paying attention to on-screen action.