OK, I've never been to Mexico. I have never had "Pulque", an alcoholic beverage made from a plant. Poor working Mexicans do though, and this doc is all about them. Unfortunately, younger Mexicans are drinking rum, so a way of (inebriated) life is coming to a close.
This movie gives little in way of historical or gastronomic explanation (what does this stuff taste like?), but concentrates almost entirely on poor, drunken people singing and drinking in "pulque" bars, singing bawdy folk songs, the main chorus of is "fuck your mother" if the crowd doesn't do what the singer requests.
An overlong, painful slice of life, and a waste of time. The 'Latin Beat' fest has many excellent films from Latin America, but Mexico went 0 for 2 with this and the music-video inspired Romeo-Juliet tale 'Love Hurts'. Avoid at all costs.