DS 'watches' tele, about as much as a 10month old can pay attention. It's pretty much theme songs, and the occasional look at the tv (unless it's giggle and hoot for which he will drop everything!) but he is too busy playing with his toys or climbing over me to be sitting still for long periods of time.
Like others have said, in moderation things are fine. Just make sure that your little one isn't spending all their waking hours in front of the tv and not engaging in any other play and they will be fine.

I personally have a rule though of tv off at meal times