I was thinking of doing a let's play (A play through with cometary) when it goes open source via the Humble Indie Bundle. I was wondering if any of you had any advice of how to record it or if I can record it in game. Also I just wanted everyone's opinion before starting it.

Sounds cool, some things think you might want to do before going through with it.

1. Play through the game once. Get really good at it, and a good overall feel for the game.
2. Play through the game using a walkthrough. Take notes on interesting game points, and alternate ways to progress the game.
3. Play through the game while taking notes on interesting trivia and facts about Aquaria in general.
4. Do some research on Aquaria, Bit Blot and it's creators and jot down anything you thin would be interesting to tell the viewer.
5. Find a good video recording program, preferably one that lets you record your voice into the videos, I'm not sure if ASW's does that.
6. Record the first segment or episode once, twice, how ever many times until you feel good about the episode.
7. Upload the episodes into a widely accessible video site, like youtube.
8. Tell people about it!

It's probably more complicated than that, hope this helps though. Good luck!