Being tarred and feathered was no joke, it was a violent and cruel form of mob justice. Yes, the tar was hot, and would burn the victim's entire body. After being tarred and feathered you would be strapped to a log and paraded in front of the town for hours. The log would be cut into a wedge shape and you would be strapped to it in such a way that you were straddling the edge of the wedge. After a while the wedge would pretty much destroy your genitals and cut deep into your body; so if the burns didn't kill you, that would.
theres a pretty good description of tarring and feathering in the adventures of huckelberry finn. It was practiced in America furring the 17th, 18th, and from the photo apparently into the 19th century. It was a form of mob justice, but of course today you wouldn't be tarred and feathered, you'd just be "cancelled."