I didn't know I'd need an extra electronics piece to make this work. The video showed a single 7805 doing the trick. Nothing about capacitors and such.

Charging my phone off my laptop would be silly, since I'd have to have the laptop on to do so, in which case I'd just watch movies on the laptop. I imagine if I left the laptop sitting at a boot screen or the bios password screen, and dimmed the video to minimal and turned off wireless, etc. I could get more time out of it, but it'd still seem like a waste.

I guess there's no harm in picking up a few cheap car chargers for my phone and seeing how they perform on the 9v battery.