There is actually a pretty cool alternative that ranges from about the same price as the Chromecast to about $80. It is called Android Mini PC and runs full Android and hooks up to your TV or monitor. Here is one for $35.
Personally, I am thinking about getting one similar to this one instead of the Chromecast. However, I didn't realize that you could mirror Chrome tabs until this thread on the Chromecast. So, I may get a Chromecast, since I could watch flash videos through the Chrome browser.
I wouldn't touch the android mini pc, very cheap construction and some pretty poor reviews
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does it stream from the mlb app?