Hey, it looks great! Visually, it's pretty awesome. Couple suggestions on the visual end:
1) The background behind the girl is a little bland. Maybe "spice" it up, no pun intended.
2) Your girlfriend should be a little more expressive. It feels stupid and fake when you're doing it, but we're used to TV personalities of all kinds having exaggerated expressions; that's the norm for TV ads. Sure, no one really smiles half that big when they bite into a TV dinner, but they do on the commercial!
A little audio suggestion: work with eliminating the "box-room" sound; it sounds like you're getting some reverb or a slight echo. You might be able to help decrease that aura by working with the sound in your editing program.
Additionally, did you acquire the proper permissions to include Doritos and the soundtrack in your video? If not, it's a violation of their intellectual property rights for you to distribute the video, even if it's completely non-profit and "just for kicks." It's unlikely to ever happen, but if they considered it damaging to their image, they could and very much might sue you. The better the work that you do, the more likely it is to catch their attention (it looks professional).
For example, they could say that not only did you use Doritos without their permission, but that your professional quality falsely represented the video as a real ad. Thus, the association of Doritos with scorpions makes a link with people that somehow scorpions are pieces of them are included in Doritos, or simply that the two have some connection; therefore, this reflects negatively on them, and they press for damages. It's happened before, and little guys get nailed to the wall.
My recommendation is to acquire permissions (which will NOT happen), or use a bag with a generic label on it (call it, "Goritos").