There are four bases, so one base encodes two bits of information. Eight bits are one byte, so four bases are one byte. 2500 megabases = 625 megabytes. So yeah, Parent was off by a factor of 5-6 :) . But still, that fits on one CD.
Except that currently genomics requires even more information to be encoded - such as quality scores, allele frequencies, phase information, ... - so, depending on the format, this estimate is off by either one or two orders of magnitude still.
