I was just trying to make a recording using record.js and well hit on a problem.
Using a mixamo fuse rig avatar, Recording using faceshift and the hydras.
When I play the recording back the avatar folds up like happens if the avatar was made in blender.
So I repeated the recording this time I loaded @davedub 's walk js and used the pre post setting (which on a none blender avatar folds it up like it was before i made the recording.
This recording played back unfolded with weird arms.
But getting to the point it seems to indicate that the pre-post rotation thing that Blender users have is maybe reversed with the record js
I then tried my 2 part judas avatar which use to work with record , that gets thrown on its back on playback