Actually, that time slot between 7 PM and 8 PM (all times are EST) is a very profitable hour for local affiliates. They get all the commercial revenue in that period (unlike 8 PM to 11 PM for the big three or 8 PM to 10 PM for the junior three). So a half hour Bush speech at that time period puts a big ding in the affiliate's wallets. Typically, they get seven to eight minutes of commercials in this period, not one or two.
Which was why the networks were willing to cover the speech -- it didn't cut into prime time and their best commercial hours.
Actually, I was assuming veritas is out West somewhere, where it would only have been 4 PM. (Of course, that's Oprah Hour...) I don't know why I assumed that, since his profile page doesn't say...