I want to offer two documentaries that deal with purity: The Virgin Daughters, which deals with father/daughter purity balls, and The Purity Myth, which deals with the problems caused by the purity ideal. The first one is available online in its totality, and that is the video you see below. The second must be purchased, so all I can offer here is a preview (also below).
The Virgin Daughters:
The Purity Myth: