As your from scotland, your player plays in a pal format. If your downloading open source movies from the internet, there likely to be in an ntsc format. As the two have different framerates, when you change the avi/mpeg4 file into a vob file, it changes the frame rate, from ntsc into pal to make it playable on your player. Because of the different frame rates, the converter has to drop frames, which means that the dvd appears "jumpy". The only way i can see around this is burning the files in an ntsc format and playing the files on a multi region dvd player.