It is probably confusing, because people keep talking about 280 downloads. That is really just marketing PR to sell people on what they can expect.
An easier way to explain it would be to say "your account generates 40 tokens every 24 hours, but you can't ever have more than 100 at one time".
*shrug*
Truthfully, and this thread only reinforces my opinion, people get really hung up on tokes, their token pool, etc. Probably for no good reason.
I think I've run 'out' of tokens like 2-3 times. And the first one didn't count, because I had incorrectly assumed that I started WITH 280 when I first got my licence key. Got halfway through a TV series before I ran out
I'm not saying the way I use AS is the 'correct' way, but as I mostly download TV (not movies), I don't have the normal 'cushion' that folks who only download movies have.
And even with a heavier usage pattern, I seldom run out.
YMMV.