The footnote says: this presentation was prepared before the Krebs On Security DDoS attacks which had a different profile and did not use Spoofed IP addresses.

The footnote says: this presentation was prepared before the Krebs On Security DDoS attacks which had a different profile and did not use Spoofed IP addresses. Krebs's DDoS attacks launched by internet-of-things devices were unusually large. Most of the non-spoofed attacks were way smaller. This does not invalidate this talk. Non-spoofed attacks are easier to block - since the source addresses are known. It is also possible to fight and eventually destroy the botnets. This is much harder when the IP's are spoofed.