Today marks two years since Google debuted Chromecast, the small and affordable streaming device. To celebrate its second birthday, the company's letting owners get in on a couple promotional offers: a free movie rental and access to 90 days of Play Music. Google did something similar last year, but back then it only included the complimentary subscription to its audio-streaming service. For those of you who don't have a Chromecast yet, the deal will be available until December 31st, so there's still some time to take advantage of this deal.