Removing horizontal scan lines from video?
If your video was shot indoors with fluorescent lamps illuminating the room, then the lines will be due to the frequency of the camera's shutter being similar to the frequency of the lights flickering on and off (usually 50Hz in UK, 60Hz in US).

It's not really possible to fix this in post production. You'd need to reshoot with different lighting or at a different shutter speed on the camera. 

See link below for more info:

http://www.davidsatz.com/aboutflicker_en.html