There could be a number of reasons, but the two most common ones are:
1) A low MTU setting on the test machines.
2) High packet loss rate on the Wan.
It looks like the test link is limited by Express at about 6 Mbps, which is equivalent to the test in the video. The silesia corpus is compressible, while the ISO compression is very limited. That should still give you +-60 Mbps on the hot transfer though.
I think start with checking the MTU to ensure you don't have something like 1300 set. Then test smaller files a couple times and see if you can obtain the 60 Mbps on the hot transfers. On the longer transfers check the CPU stats to see if its not perhaps a bottleneck.