Editing video from portable external HD with thunderbolt?

Do you know if I can use a portable hard drive like the G-Tech G-Drive mobile with Thunderbolt to edit video in iMovie from my 2011 Macbook Air? I'd like a drive that I can use to edit directly from and not just store data, but I'm a casual video editing user; I don't do anything fancy so I'm hoping not to spend toooo much. At the same time, I'd like it to work without being too slow. Thanks!