@FaLLeNOnE
I know what you are trying to say by 'scanline' now...
You seem to misunderstand the term.
A television usually has 625(PAL), or 525(NTSC) scanlines which are interlaced.
Lets use PAL as an example of what happens:
PAL uses 25 frames per second. Which is made up of 2 'feilds' per frame. So there are 50 of these feilds per second.
Each feild is drawn by 312.5 lines down the screen(some are hidden - sortof).
Each one of these lines is a 'scanline' or 'raster (line)'.
What you seem to be talking about with the camera, is where the camera and TV are slightly out of sync.
The part that looks abit wobbly when you shake the camera from side to side, is not called a scanline, it moves up or down because both devices are not starting the drawing of the display at the exact same time. One starts to draw its display while the other is in the middle of its.
If the gap is moving up or down, then they are not at the exact same frequency, they both might be about 50Hz(interlaced) (or 60Hz for NTSC), but they are slightly different.
I hope this helps clarify things... :-)