Assuming a podcast is 50MB, that would be 300k podcasts. If I'm about to jump on a flight, I may download 4-5, which would put that at about 60k people. I just found an article saying 53 million people flew through SFO in 2016. If we distribute those evenly (unreasonable, but ballparks it), we get just under 145k passengers / day.

Obviously web pages and mp3s are much lighter than a typical podcast, so this isn't the best methodology. 15TB is a lot, for sure, but on the busiest travel day of the year, I can rationalize it.