It's there in theory but in practical application it just doesn't work the same. Here is the positioning of CAT, which is the same as any custom bone rig. Biped rubberband mode has you select the joint higher up to move the position of the lower. If you want to move the elbow you select the bicep which has its pivot not in…
I was never really sure if Skin used it or not and never looked into it, thanks for the links! I make use of the "assume skin pose" while animating just to get pieces back to a clear starting place. It also seemed to help keep the biped clavicles in place, where before I started doing that they would apply a universal…
The CAT gif is from an old example I had sitting around in my dropbox, the biped one was fairly easy to crank out. Two ways... 1) render a viewport preview to AVI, and import that as layers into photoshop, then the animate panel has a "make frames from layers" option. Some newer versions of photoshop might be missing this…