Question: Is the 8gb SanDisk I have, good enough and big enough for the job?
Odd that Nikon didn't include a video capacity chart in the manual like they did for stills. No problem tho...
Just select your desired video and audio settings in the menu, turn on Live View and start recording... the estimated time left on your card at those settings will be displayed on the LCD. I get 20 minutes (for 1920HD best quality with audio) on a 4 gig card so I assume you would get twice that. Actual size varies by content tho, just as with jpgs... scenes with little action or camera movement, or with uniform brightness or low detail will produce smaller files. But I'm guessing that for eight 3-minute vids, you're probably good to go.