While not having done this experiment in particular I do have experience in distinguishing a lot of the relevant qualia and what mimikry does for emotional transfer.

In a study they got 31/108 to feel pain when seeing images/clips.

The sensations they felt were most often described as “tingling”, followed by “aching”. Other descriptions included “sharp”, “shooting”, “throbbing”, “stabbing” and “tender”. The pain was described as lasting for “a few seconds”, “fleeting”, or “for a split second as soon as the picture appeared.”

That's a simple picture without any rapport building and more than the 20% in study you cited report feeling pain.