Yes, there are variable frame rate in original video. It's common in anime. Something like about 9 - 23.98 FPS. You can also notice that in one frame, different object may have variable FPS. It is oldschool hand made masterpiece. I've made simple test video to compare it with other videos of same scene from other RU-vidrs. Maybe later I'll try make it smooth constant FPS, but it would take many work manualy with every frame.
