Same reaction here - this is based on the premise that the data was transferred directly from the DNC server to somebody's home connection, and doesn't allow for the possibility that it was first transferred to some server in a data center.
https://blog.serverdensity.com/network-performance-aws-googl...
Just some random article from 2014, look at the data points for transfers between data centers where anybody can rent servers:
Amazon "us-east" <-> "us-west" 210 mbit/s
Google "us-central" <-> "europe-west" 189 mbit/s
Rackspace "Dallas" <-> "North Virginia" 534 mbit/s
Softlayer "Dallas" <-> "Amsterdam" 61 mbit/s