I might be half asleep (it's currently 2:02 AM over here) and not seeing it, but the MCH-arm_properties_widget bone appears in green but doesn't have a constraint box attached to it. I watched all three arm videos back to back and started working following the document after that. I think I got everything working as intended, except my properties bone scales when I take my IK bone far apart :/
Rodrigo... It took me 2 or 3 tries to get it all working correctly the first time I gave it a go :D It might help if you were to post some images showing what you have and perhaps someone (maybe even Wayne) could see what you're missing.
Thanks for your answer! I think everything's ok for the most part, but I think the gear shouldn't scale with the IK bone. Looking around, I figured it's only this missing constraints on the document for the widget

Like I said... It took me two or three times to get it working. I'm not sure what I messed up the first time around, but I did get it working using the schematic he provided.
Hi Rodrigo,
Yeah there might be a error on the document, but it should be the same as the legs. Your legs are working correctly yes?
I will have a proper look tomorrow when I'm back at work but I think you want to parent the widget bone to the properties bone, and have the widget bone damp track to the MCH-Forearm_switch.
But just check the legs, the answer is there.
Hope that helps - but I'll take a proper look tomorrow.
Hello, thanks for your answer! I haven't gotten to the legs part yet, I'll do the fingers today and maybe I'll have time for the legs too. I'll check the document still to compare and see if that solves the issue