Note, though, while there are not explicit bandwidth caps, their terms of service does say:
If your bandwidth usage significantly exceeds the average bandwidth usage (as determined solely by GitHub) of other GitHub customers, we reserve the right to immediately disable your account or throttle your file hosting until you can reduce your bandwidth consumption.
My impression is that GitHub would much rather we ask permission than forgiveness. Make sure they know what kind of bandwidth we expect to use and are OK with this.