ok but maybe the dont zoom option is only meant for the 4k girls...
No, that is exactly the wrong conclusion. The "Don't zoom over 100%" is is meant to apply to the lower resolution cards - those are the ones that ***** most from being enlarged to fit the screen. Unless you have a screen with a higher resolution than 4k any 4k clips will need to be reduced in size to fit so restricting the zoom to be no higher than 100% can have no effect on them (unless you deliberately configure things to concentrate the girls legs by setting the size slider to well over 100%).
Ticking it optimises for video quality but in order to do this you have to sacrifice equalising the heights unless you want to equalise to a low height. A 480p image has only 1/9th of the pixels than one that is 1440 pixels high (only 1/16th of those of a 4k image) and even less information than that when you take the colour depth into account. If you try to blow up a low resolution image you will inevitably end up with a poorer quality result than that you would have starting from a higher resolution.
If you want the girls to have roughly the same size then untick the option and adjust the size slider - you should get the result shown by
@Dorsai6 's second post. Or you could tick the option an reduce the size until the highest resolution clips have the same height as the lowest resolution clips - then all the girls should appear to be equally short.
However, if you want the best video quality then tick the option. The 480p and 720p clips will still have lower quality but not as poor as it would be if you try to enlarge them over their natural size. This is because they were recorded years ago with lower resolution cameras - good resolution for the time but poor now. (Actually if you just want the absolute best video quality then tick the option and set the size slider to be well over 100%, the clips will then be displayed at their natural resolutions but those that have a higher resolution than your screen will be much taller than the screen so you probably will not want to do this)
when it was unchecked the girls were too tall to me
Then use the size slider to reduce them to a size that suits you - that is what that control is there for.
guys i tried unchecking the dont zoom option and i played a 720p card...comon guys cant you see it looked terrible
Yes - that is what we have been telling you. You can optimise for video quality or for equalising the heights but not for both at the same time. Even if you optimise for quality the high resolution clips will look better because they have inherently higher video quality anyway. You can't put in details that were not recorded when the clips were shot - in the case of 480p they were originally recorded on video tape.
Now, it does seem that Totem use a very simple - but efficient - algorithm to to rescale the videos. They could use a better one which would improve matters somewhat, though there would still be a very visible difference in quality, but this would be at the cost of higher CPU usage which in turn could cause the playback to stutter, jerk or be slow.