said by quetwo: Not entirely true. He's using VPN bonding in a round robin configuration. I'm using a similar method (albeit over a single connection so that one download is actually equal to two connections - improves my download speeds at long distances).
Unless he has Verizon's partnership, he won't get 300Mbps down on anything. Verizon has to bond the connections (aka load-balance), or data will only come in the route that requested it. Sure, he could load-balance the requests on his side, but he won't ever see more than 150 Mbps on one download.