There is no transport technology, even in the internet backbone, that reaches 1tbs.
The Backbone is multiple 40gbs trunks, meshed.
1tbs to a single target is just not possible.
The first "D" in DDoS means what?
Sounds like they are talking aggregate of all traffic across their network and not just one data center. These memcache servers are hosted on their isp’s own network at times.