“There can’t be many new DVD releases of short film anthologies which are unstintingly riveting all the way through. But here’s one. For the past couple of days, I have been glued to the BFI’s incredible collection The Joy of Sex Education, which is a compendium of sex education films from 1917 to 1973. They have a weird similarity to old-fashioned stag films, not merely because of explicit content, but because they are designed to be watched in a semi-clandestine world….”