It appears that the following will be in free preview:
Universal Sports Network
Wed, 02/04/15 - Tue, 02/10/15
Always available in Mult-Sport Pack
107- Comedy Central
Thu, 02/05/15 - Tue, 03/03/15
Always available in America's Top 120
111- DIY Network
Thu, 02/05/15 - Tue, 03/03/15
Always available in America's Top 200, Smart Pack
124- BET
Thu, 02/05/15 - Tue, 03/03/15
Always available in America's Top 200
170- Nickelodeon
Thu, 02/05/15 - Tue, 03/03/15
Always available in America's Top 120
Science
Thu, 02/05/15 - Tue, 03/03/15
Always available in America's Top 200, Smart Pack
208 - CNBC
Thu, 02/05/15 - Tue, 03/03/15
Always available in America's Top 120
[Source:
http://www.mydish.com/perks/free-preview]