Original File Fine, Output File Noisy

I did some editing and such on a .mov file last night and when I played it back it was pretty noisy. I thought maybe it was because I shot from the hip so to speak before I learned about doubling the frame rate for shutter speed etc.

However, I happened to play the original file today and notice it is not noisy at all, so somehow in post processing I introduced the noise?

Thanks,

Ginger