I do not do performance capture. Most of my work... 30+ years has been with Aftereffects. I need to be able to keyframe the entire animation.
there seems to be no way... either because there IS no way, or... it's just not documented where it can be readily accessed... to keyframe the position of handles in a rig.
this renders the rest of the features in Character animator completely useless to me. as nice and desirable as they are.
also: write it down. if you have an urge to make a video tutorial about something... write it down in the documentation first. Videos often have minutes and minutes of non-helpful 'content' for people trying to answer a single question. if it's that important that you think it deserves a video... write it out in the documentation first.