The video explicitly states that the browser+ec2 work together to decide how to divide up the work based on network conditions, page complexity and other factors.
I would assume that to mean that if there's Javascript that can't be run on the server side, it will be run on the client.
How's it mind boggling that a single SPDY connection to a distributed network that has nearly unlimited bandwidth and computing power would be faster than having a mobile device negotiate its own connections?
Even if it was just a proxy for resources it would be way faster, but they gain the benefit of knowing what resources are needed based on past events and likely already having them cached. Not to mention all the sites that will be local to AWS.
I would assume that to mean that if there's Javascript that can't be run on the server side, it will be run on the client.