apologies if this is dense but what is the ik-enabled mixamo rig you are using in the demonstration video? I haven’t seen that before and would love to use it.
It’s not “IK”, it’s just bones with custom shapes being moved using AutoIK because it’s far more convenient to pose with than manually selecting individual limbs and rotating them.
No, that’s not some sort of obscure addon, it’s a toggle-able property that temporarily adds an empty IK constraint to use it’s math to quickly pose things.
unrelated
The regular version shown in the video require bones to be connected. I have an addon that does it for the entire body.
Before, I would use hidden “filler” bones where I would prefer the bones stay separate from each other. This also means it has the “option” of disconnecting (for stretch)
…yes, I know it’s “technically” IK but it’s not really IK though 
Ah I see. Thank you for the info.
What is add-on that applies the AutoIK to the whole disconnected body?
No name
Unreleased
One of my many toys that I just make to “test” an idea, then actually flesh out into something more.
This one’s idea was how I could fix 2.8’s autoik issue where it doesn’t keep the chain length set.
See, before you would have this global chain length (shown in the header), and that’s the value that the temporary IK constraints will set for their chain lengths. When you start moving, they’re automatically set to this and that’s it.
In 2.8, when you start they ALWAYS have 0 as the value, and only use the global length when you tweak the global length. Which means you always have to do at least one extra click (mouse wheel/scroll) for no good reason.
When I got the base process to actually work, I knew I was going to just pile on to it.
The “full-body” thing is just a “thought” I had about how the Default IK works when you grab the parent that’s connected to a chain with its children.
(https://streamable.com/tqxf4)
Even got this secondary thing working where targets from damped tracks can be dragged along with the bones. This could mimic that snake-hook thing that some other IK systems demo while playing around (https://gfycat.com/candidmediocrebordercollie)
Gee willikers! that would be an awesome addon release. It looks like Design Doll levels of posing comfyness
Hi thanks for the addon 
İs that can be used in blender 2.81 also ?
Additive layers is builtin. Addon not needed.
If you're talking about something else, yes and no.
The code isn’t directly set to work but all code can be easily tweaked to "work" in 2.8.
I was slowly attempting to port all my stuff (this and unreleased) to 2.8 (with backwards compatibility) but then I started making new stuff and eventually dropped the idea of 2.7 backporting.
I kept old code nearby as maybe-todo for porting to 2.8 but I basically dropped them (unofficially)
Same for this addon: I basically abandoned it (unofficially).
The big thing is redundant, and little-to-no interest in the other stuff, so why bother 