I bought a WD 1TB hard disk, windows 7 pro, a webcam, and Left 4 Dead 2. Lots of sales were online, newegg.com had the best imo.
I'm not sure if the numbers are accurate, but I think they were calculated either from companies that consented to monitering their sales long before black friday hit, or these are spending reports from major credit/debit card companies. It's not as complicated of a calculation as you'd think. It's not like people all flocked together all at once and said, "Lets throw our numbers together right..... now!" This was a planned calculation, don't overdue the thought process behind this calculation.