Streaming video from shared Mac folder to AppleTV? I just bought a new AppleTV and will be getting it soon, and I want to know how I can stream my movies which are located on a shared drive to it?

Right now, my videos are in a folder which is shared by my MBP (which is running SL) and have various formats. I've been trying to find a way to show these on my ATV without having to convert them.

I've heard about AirFlick, but I'm running Lion and apparently it doesn't work (someone tell me I'm wrong). I also vaguely remember a way to stream it to my iPhone4, and then stream that to AirPlay on the ATV?
You are right about streaming to the iPhone (or iPad) and then to the ATV. Check out the VLC streamer. The application is installed on iOS, and a companion app goes on the computer. VLC Streamer will transcode non-native video (e.g., AVI) from the computer, pipe it to the iOS device, and then pipe that to the ATV via AirPlay. I have tested this and it works exactly as described. The quality of your results will be dependent, of course, on your LAN bandwidth and processing speed of the machines. You can set some of these parameters in VLC Streamer, though, which maximizes output. Enjoy!