When doing this, I find myself starting with an upstroke... before I made my first post here I checked out the video, Gilbert himself starts with an upstroke at each section.

I don't know wether it's wrong or right, but I don't like to stick with rules , the only rule I believe is that you should do every thing with the least amount of effort, so that you don't get tired if you speed up.

The easiest way of picking may differ from a person to another due to a lot of physical reasons .

Anyway,you should try this at slow tempo , find the easiest way of picking that suits you then develope your speed gradualy.