Just to second what Zeds said, it will work but will keep you waiting while complex stuff renders, exports, imports, etc more often. It really depends on your usage. If you are planning on editing your own family vids or whatever then you will probably be fine. If you were to use it to edit wedding videos for a small business you mind start pulling your hair out waiting for it too often.
I am considering selling my ipad to partially fund one of the new airs myself, and although I wont throw anything too complex at it, I do plan on doing quick edits of my videos from my Canon 60d to upload on youtube. Anything beyond simple editing and I will sit down with my powerhouse desktop.
As long as you have reasonable expectations you will be fine with the MBA.