What do you mean transfer?
You have two main options to keep them the right way up on the eventual screen regardless of how clever the video program tries to be/original video device tried to be.
1) Crop them down. Cropping loses information and I have yet to see a sufferer of vertical video syndrome frame shots such that cropping is straightforward or even all that viable.
2) Stick massive black bars (or you could do the ever fun slightly washed out and blurred zoomed copy of the same video as background effect I guess) on the sides such that it becomes 16:9 or whatever landscape aspect ratio you care to use.
If you have massive vertical resolution then that can get a bit harder if you want say 1080p and your vertical res is more than 1080 (a 1080p camera would have 1920 vertical after all if you turn it on its side). You can happily scale something down but again losing information. Alternatively if it is black bars you and keep the high res vertical and go that as black bars don't add much to the eventual storage space.
Any vaguely competent video program will handle all that that really.
If they are all the same resolution to begin with and you just want to do black bars you can probably make a script to do it (any more than about 15 videos and I would but your patience for repetitive tasks might be higher than mine, or you might just be able to knock out some ever evening until you are done).
I personally like avisynth (text based editor) and with that you could probably make a nice and simple script where the only thing that changes is the name of the clip in question it gets to load (I could even automate that part with very easy stuff as we do it all the time for ROM hacking).
Crop and black bars are both basic options (
http://avisynth.nl/index.php/AddBorders for the adding borders), though overlay might do better if you create a blank clip of all black (or whatever colour/image you want to use). Overlay will also be how I would do the zoomed (resize larger and crop), blurred (blur or blur filter) and faded (drop saturation with tweak) effect .
I would keep the originals as well if you can (assuming you don't do lossless) just in case you do want the best quality originals. Mind you any video player of any great worth today and going forwards should be able to handle such a thing so this largely seems like a redundant exercise.