I assume these aren't XB1X's in the building acting like an Azure server like MS said would be possible?
What are the odds the connection being used is Google Fiber? lol
The connections in such big events are the best one can pay. But for latency internet speed doesn't matter, but the distance between you and the datacenter + the route the data takes on its trajectory.
And they are claiming the closest data center which was serving the stream at E3 was 400 miles away. If true, then game streaming tech has gotten a huge leap.