Did you take the video in the right format?
When I first filmed a video and loaded it onto my computer it didn't appear
I looked again at my camera manual and found that in order for it to appear on my computer I had to make sure that the camera video setting was for JPEG.
Since I changed the setting, it has always downloaded to my computer.
With my camera, I have the choice whether to film in AVCHD (which is the best setting for playing on a TV) or JPEG (which is best for e-mail and playing on a computer).