This is the same problem I have with big game devs, they knew exactly how many people pre-ordered, once you realize you are are selling more than you expected then you immediately take that into account and make sure you have the bandwidth to cover that number.
Common-sense issues always annoy me and this is an issue that happens time and time and time again in game launches so by now every game developer indie or not should know its an issue.
Technically they could have posted the download to tons of offsite sources for free. Gamershell, MMOsite, Fileplanet...
They chose not to, so really don't have much sympathy for the "oh so many people are downloading " excuse.