Error with finished video

[Vanavery145]

If I add a clip to the project timeline and try to play it, it will skip/glitch/pixelate every second. The original clips don't do that. After I finished making the entire thing the video still did it, even in windows media player. I had a similar problem in x7 but when I finished the video the end product would come out fine but in x8 it isn't correcting itself