I have not been able to keep the legs (or to be more precise , feet ) firm in their place when I want to do idle animation. I usually put an IK connected to the upper leg and shin, but still the feet move a bit. For what I mean look at this animation show-cased here:

Not to shame the guy who did it, but I just wanted to show a quick sample (I don`t have access to my files right now). Can someone please tell me a good way of making the feet stick in their place for idle animations?
Did something like that in my recent video, though it did not call for it to be as precise as is usually the case: