YouTube is giving out three free months of YouTube Premium to subscribers of YouTube TV. However, in order to qualify, you must have never used YouTube Premium in the past otherwise you'll only be eligible for one month.
After ending a long-standing feud earlier this year Amazon and Google have now begun starting to play nice with each other. The latest evidence of that is the announcement today that YouTube TV is now available on Fire TV devices.
A long-running standoff between Amazon and Google has come to an end, with both companies announcing this morning that YouTube is coming back to Fire TV and Amazon's Prime Video app will be updated with Chromecast support by the end of the year.