I have a WMV file that's 5 hours long. It's mostly just a camera focused on the entry door.
Is there any software where I can throw this file at it and it would find time segments where there is actual movement?
You can try this CodeProject article on Motion Detection Algorithms. Looks really good. Software is freely downloadable and modifiable.
Get Webcam Zone Trigger - you can use video files as input.
Add a motion detection hot spot on the door. Set its action to take a picture or to make a noise... go to the settings and enable text logs if you want to get a list of all offset time where motion is detected.