[wao]

The ending animation felt more like tons of smooth in-betweens with somewhat detailed movement, more than motiontracing (rotoscoping?). They did a good job making sure the face moves slowly while the character does a motion so that it looks more eye-catching. But rotoscoped things have a bit more movement, than that, I think (you'd see the hair and stuff move a bit more).

But I'm not an animator or anything like that so I can't really say for sure...