Sometimes my dogs look at the television, but I'm not sure if they're actually watching. I haven't seen any connection to a particular image or sound. I think they just notice the movement on the screen and have learned to ignore the noise.
The resulting commercial, for their Beneful dog food, features a squeak, a high-frequency tone (that humans can barely hear), and a ping noise. Purina also said that the commercial also features whispering, which they found was successful in gaining dogs' attention, although I didn't hear any whispering in the advertisement.
The commercial was released in Austria and can be viewed below. When I played the commercial, my dogs didn't seem impressed. I didn't even see an ear move towards my computer.