Fun video, however the legs of a housecat are not designed to walk upright that is why it uses this method that would be very hard to walk like this, I however saw a video of a dog with no front legs who walked digitigrade on its back legs, and as other has said, all birds do it, even ostrichs who ate both heavy and can run pretty fast.
It’s no issue to walk on two digitigrade legs, stand up, lift your heels of the ground and walk forward, see not hard at all, yes you get tired very fast because you legs is not designed for it: to shallow angle between your toes and heels and no support but far easier than walking on your knees.
Back to the game, main problem with digitigrade characters is not only their feet, its also that the legs would look different, I made this myself, http://www.youtube.com/watch?v=Hy8c-YYdB4g
The lower bone on the leg might be to long however the chin bones has to be far shorter than on a human, the knee joint is also a bit higher. The result is that the model for pants would not work, neither would the rigging for skirt or robes even if you could use the same model.
Morrowind get away with this but the result was not very good.
Speaking as a lifelong "toe-walker", I can say it's not really that tiring, if you don't stand still. Gotta keep moving, but the advantage is it's a
lot easier to start moving, stop moving, and change direction than plantigrade movement.
And normal pants models do work... you just have to shorten them by 20(My model)-33(Your model)%, and the structures line up.
In your animation... that cat has two heels >.< (The balls of the feet extend too far back), and skirt/robe meshes would rig properly even to that (her tunic mesh demonstrates). Also... I don't quite like it because the width of the foot below the ankle tapers way too much... it shouldn't taper at all (There has to be room for four parallel bones in there).
In my opinion, the best way to convey digitigrade bipedal movement without looking too weird is to have the arch of the foot be 1/5th the total length of the leg (As viewed from the front from a neutral stance), not 1/3rd. The shin and knee should be 2/5ths each. (Normal person has shins and knees be 1/2 each, and the arch of the foot doesn't extend beyond the heel)
For walking... the plane of the foot including the ball and toes of the foot should remain almost parallel to the ground at all times. The shorter distance also allows for lower pitch with the legs, making the structure more identifiably "Human" from a distance.
People need to stop including the foot as part of the leg.
I had no problem with Oblivion's khajiit, aside from the shape of the foot.
Colovian Fur Helm, Glass Helm, Netch Leather Helm, Nordic fur Healm, Dreugh helm, Imperial Chain Coif, Imperial Dragonscale Helm, Imperial Silver Helm, Imperial Steel Helm, Imperial Templar Helm, Nordic Trollbone Helm, Helm of Oreyn Bearclaw, Adamantium Helm, Wolf Helmet, Bear Helmet, Stalhrim Helmet and Nordic Mail Helmet.
There were quite a few. A lot of these were even some of the best of a type. And even if this isn't enough, this is a new game. Why can't Bethesda simply make MORE open helmets?
Khajiit don't bother me quite so much, it's the Argonians I want to see extremely different, but again, you're linking Nirn physiology to Earth physiology. Stop it. Bethesda can make up thier own laws.
http://adul.net/?p=dl_mwmods_aduls_leggings
It's EXTREMELY simple.
Crossed out and colored the helms beasts couldn't wear in that list. And I'm all for more open helmets. I don't like closed helmets. They aren't heroic. Full helmets are "Kill me. I'm a Faceless Nobody" signs, unless you are playing a Black Knight.