Thanks for the link. As they say in the video though, latency issues depend on the game's implementation. From [1]: "If the game does like a read-wait-read-wait pattern, then it's bottlenecked by the latency... and that can become a problem."
Halo presumably has a solid streaming foundation, so it's a good fit for the service.
"Server Side Prediction: Via servers are constantly learning from repeat access patterns of players. This let's us make high quality predictions for what content you'll need, before you need it."
This video shows a good demo of it with Halo on Steam.