I don't know much about mondo except that it's mostly exploitation, sometimes racist, and occasionally just stagey lies. However, Ecco is highly entertaining in its variety of rituals from different cultures all over the world. I had to Google the reindeer thing, and it's actually true (or once was before it was outlawed). There's also some reasonably tame but historically accurate presentations of burlesque dancing. This isn't the sort of documentary that you could share with the whole family, because of the adult content and also because with mondo cinema it's unclear what is real and what is exaggerated or staged. But this one's fun!