Television programs today haven't quite reached the level that they have in Mildred's society. In her society, the screens are so large that they are called "walls", and the shows are completely interactive, meaning, you can be a character in the shows themselves. You get a starring role in the shows, and the programs interact around you. However, we are getting close. Take for example the increasing size of televisions. And, a lot of people have special "theater rooms" where they use a projector to project the image onto the entire wall. So, it is not a stretch to imagine that extending to cover all 4 walls of a room. Also, technology is increasing; video games are already interactive, so why not apply that to television programs? 3-D movies are more and more common, which make you feel like you are right in the middle of the movie. So, the pathway to Mildred's level of entertainment is easy to see. Bradbury's novel, a dystopian novel, takes our society today, and projects to what it might possibly be in the future. As far as entertainment goes, Bradbury seems to have been pretty insightful, as it is easy to imagine t.v. parlors like the ones Mildred uses.
I hope that helps; good luck!