1080p video shows up slow on computer?

I recently got a Nikon 3100 Dslr camera and I took a video and uploaded it to my computer via iphoto (I have a mac) and It plays back really slow and glitchy. The audio is fine however. I'm concerned whether Ill be able to make videos with the camera since the clip i uploaded was only about a minute long. Is there anyway I can make the video play correctly on my computer?

Your computer probably can't handle that type of quality.

It sounds like the graphics card in your mac can't handle the 1080P definition. If you were to burn it onto a disk and play it on a dvd player to your TV, i'm sure that it would turn out fine.