Note that the alternative is to stretch the display to fit the screen. You're not going to see more tiles or anything. Maybe see if you can record an area of the screen instead? Or crop the video area afterwards?
Pressing F5 should bring up the Video Options. That has an "Ignore aspect ratio for stretching" option. I think it's greyed out in my screenshot because I've disabled it globally on my system.
I'm still undecided weather or not I should add minor swearing to my game. Like I'm going for an all ages demographic... but the idea of a cartoon character saying dammit, hell, or crap in normal conversation is really funny to me.