The name of the documentary is " The World's Biggest Penis" that aired earlier this year (January) on Channel Four (UK). I downloaded it on a BitLord site. IMHO: It was not that exciting to watch. Below is a description:

Here is a link: http://www.mininova.org/tor/215093

The World's Biggest Penis

The bittersweet gift of having what every man wants!

No doubt about it, society celebrates the big penis. Seen as a sign of adequacy, virility and manliness, those lucky enough to be well endowed are heralded by both sexes and all sexualities. As women have always maintained, and men have always thought, size matters, but not in the way that most of us imagine. Sometimes having a Big Johnson is a bigger problem than you'd guess. THE WORLD'S BIGGEST PENIS reveals there is a bittersweet side to nature's gift, lifting the veil on a taboo subject and showing the reality of what it's like to have what all men dream of.