If the video footage that you want to edit is on a tape you'll need to hook your camera or tape player into your computer. Plug in your camera's AC adapter so it stays powered while importing. Turn on the camera and put it in VTR or VCR mode (so that it plays video, instead of recording it). Now, connect the camera to the computer using a USB or FireWire cable.
From the Capture Video menu, select Capture from video device. This opens the Video Capture Wizard which you use to import video clips.
Using the controls on the camera, advance or rewind the tape to just a few seconds before the scene you wish to save. Play the tape, and press Start Capture when you want to begin saving to the computer. Hit Stop Capture when the scene is finished.
The video is saved as clips, in the proprietary Windows Media Format. The Capture Wizard lets you know how much video you have imported, in terms of time and file size. It also tells you how much space is left on the drive.