According to this article, a couple of football matches (say 4 hours, with leadup and post-match?) at the 720p that NowTV runs at will be somewhere North of 8Gb, so 10 isn’t out of its tree.
To get it in 4Gb, you’d have to watch in SD, which NowTV doesn’t do.
But are you on a metered connection, given that you are worrying about this?
How would the Stick having the 5Ghz band help with your data consumption?
And presumably, you are going in the opposite direction to all those clamouring for 1080p so you can watch the footy in 480i fuzzyvision?