I spotted that insert with my bill about a WHOLE WEEK of free HBO, Cinemax, and Starz. I don't think DTV has ever given a "free preview" this long or with this many competing premium channels. Last year, there was a free preview but it started the Wednesday of Thanksgiving week and ended late Sunday night.
These free previews are designed to get you to watch the series that the program providers are running and like them enough to become a regular subscriber. In the past, the premium channels content was 90% or greater movies but now with so many other ways of obtaining movies they have to do something to justify their outrageous monthly fee.