It took me a few WEEKS to fully wrap my noodle around this concept of weekly increase when the limits you are seeing are MONTHLY limits.
So your 2+bonus terabytes of bandwidth are "renewed" after each "billing cycle". For a long time I had assumed that since the limit was so unbelievably big that it had to be a "starting balance" while the bonus bandwidth was what was added to it every week. If I used up everything I was out until the next week.
I was wrong (and some of the DH staff agreed that it's confusing to give weekly bonus yet measure monthly).
That's freakin' huge.
The upgrade is absolutely painless. Just don't drop from year/2year to monthly, you'll get busted for the setup fee.