I wouldn't expect a child to watch any television at all in pre-school. Pre-school lasts for 2.5 hours a day - children should be organised into activities or playing with each other during that short time,
But the OP isn't really talking about pre-school - she is describing a daycare nursery with a "pre-school" room. Given that the nursery day lasts for up to 10.5 hours a day, and that these are (I presume) 3-4 year olds, a couple of hours of well-chosen TV doesn't sound appalling. Not fantastic - but then, on cold wet days my daughter (3.8) often watches a couple of hours of DVDs all told - Angelina Ballerina, Charlie and Lola, Pingu, National Geographic wildlife films etc.