My laptop will only import the sound from videos, not the picture.

I’m working on a school project in which I have to put together several short video clips into a movie in Windows Movie Maker. I filmed all the clips I needed on my family’s Sony Handycam, and tried to upload them to my Lenovo laptops hard drive. The import went just fine, until I tried to open the video, just to double check that the import worked. When I opened it, no picture appeared, but the sound from the video came through loud and clear. What do I do? I have Windows 8 if that has anything to do with it.