slightly confused by the term balance here - to me, the size of a channel is it's capacity, and it's balance is how much is on either side -

eg - if a channel is 50/50, or 80/20 on either side, that is the balance

the capacity in both cases would be 100

the explanation seems to be(?) using balance to describe both balance AND capacity, arbitrarily - but i could just be misunderstanding...