We have some good news, and some bad news. First, the good news: Redbox Instant was just updated with support for the Nexus 10! Now you can stream movies to your heart's content on that big, beautiful display. Fantastic.
And the bad news: it still won't work if you're rooted. So, if you were rejoicing that you can finally use it on your N10, you can probably stop now if it's rooted.