Before DD was about 18-20months i didn't even attempt discipline that relied on her having control over her actions. I would tell her not to touch something, but while physically removing her. Babies have no impulse control, patchy understanding of language (i.e. "Don't touch the tv" is very hard for them to understand and they usually understand you to mean "touch the tv" because the concept that one word would reverse the meaning of the whole sentence takes a bit of time to get used to!) and a total lack of ability to see ahead. Even a 3 year old finds it hard to predict the consequences of their actions, a baby under 2 has little to no chance.

So in your situation njd i would tell DS he's not to touch the tv as i lifted him away and gave him something else to touch, preferably something flat and bright (like the tv). When DD was small one of those magna-sketchers (with the magnetic pen and screen with metal filings behind to "draw" pictures with? kwim?) was excellent for her to explore the tv-like properties without wrecking a tv. DD is 3 in April and she STILL touches the tv!

My warning system is a 3-strike one, but i never threaten her. My process goes:
"DD please come back from the television, it doesn't like to be touched"
"DD come and sit here please, right away from the television"
"DD i've asked you to come here and you're ignoring me. Would you like to come away from the tv and sit/read/whatever with me? Or would you like to go and have some time out to think about listening to Mama?"

If she is touching the tv because she's curious she will usually stop on the first request, or sometimes the second and she NEVER takes the time-out option. However if she's touching the tv because she knows i don't like her to (which she does on occasion, ALL kids test boundaries afterall) she ignores all requests and usually ends up sitting on the stairs thinking it over for a minute or two. I generally use the time she's out there to plan a far more engaging activity for us both.

Smacking to me is one of the most interesting aspects of discipline and shows what clever creatures humans are in some ways. In studies if you get a rat and put it in a cage with an object you don't want it to touch (they've done this with different colours, like a black ball and a white ball) and set up an object-linked punishment (i.e. you electrify the black ball so if it IS touched it delivers a small shock) the rats learn very quickly to avoid the black ball. If a technician uses a rod and visual observation to punish the rat with a shock everytime it touches the black ball, even if the technician manages to shock while the rat is ACTUALLY touching the ball, the rat very quickly begins to avoid the rod and the technician and it takes days and days of training to learn not to touch the black ball. The fact that some parents say they smacked their kid once and they never did whatever it was that got them the smack again means human children are capable of quite amazing levels of reasoning and logic. Of course it could also be that parents perception is skewed - the rats with aversion to the electrified black ball stayed averted for many months after the training was completed (years and years in rat-time) but those who learned from the rod lost the aversion to the ball within days of training ending and never lost their aversion to the rod and remained nervous around the technician. I know lots of kids who, once smacked, don't repeat the crime THAT DAY, but the next day might the lesson about the object is usually gone though the aversion to being smacked remains.

Bx