All menus (which if you look close are animated backgrounds) and introduction animation are in NTSC which has less scan lines than PAL. When you make these NTSC based graphics play back in PAL mode the scan lines bunch up hence the black band at the bottom.

You cannot switch between NTSC for menus and PAL for playing/recording. Worse still these animations are not a standard MPEG stream - they are proprietary - so you cannot simply copy them to your PC stretch them and place them back. It simply won't work.

If you want "perfection" in the menu department you go and buy a Thompson UK TiVo which are much more expensive and supported much less by virtue there are not many of them here.

Other than that if you have a lot of time and the knowledge you can try making TyTools in reverse. That is, TyTools can convert a Ty video format to MPEG but nobody has made it do the reverse. Do that and you might be in luck.