Your code speaks for itself only to people who care about code. Which, as it happens, doesn't include a lot of investors, co-founders, customers, employees, and all of the other people you're going to have to persuade if your startup is going to be successful.

Heck, even if you have a "smarmy sales-dude" as a co-founder, you'll still eventually be in a role where persuasion/leadership is more valuable than coding chops. What percentage of successful startup CTOs do you think code on a day-to-day basis?

I think that's a little arrogant of a stance but that's not to say I don't agree with some of your points in you first post.

In my experience, I think you should consider working on your verbal communication skills. Nothing turns me (more importantly, team members and investors) off more than an ego-centric engineer who thinks their code is god. This can have a lot of implications in your product's quality and success on many levels. It's like the leader singer of a band thinking he knows best, most of the time the band ends up dissolving.

Of course YC won't be basing their decision solely on the video, it's just a very valuable piece of input. If your best voice is your written voice, you might want to partner up with a guy that has technical depth, but can also give a wicked in-person presentation.