It sounds like you need the Vision 7 Development Module for LabVIEW. This software module includes all of the VIs needed for image analysis and machine vision. With version 7, you can now read and analyze AVI video files.
Let me know if you have more specific questions. Otherwise, call NI for more info on the Vision Module for LabVIEW 7 Express, 1-800-IEEE-488. (800-433-3488)
Cheers,
KyleV