Hmmm I dont know if I am on to the right thing at all, but there was something that happened on Big Brother in the UK (series 1) when a guy (Tom) was giving a girl (Mel) a massage and he got a hardon.
I trauled the darkest corners of the net and found one lonely video on youtube which has a split second glance at the hardon in question - You can watch it
Here at the 1.10 marker.
I also added some screen grabs of the split second peep. I know this is most likely not what you're looking for, but its a possible step in the sort of right direction...kinda.
I will continue to look for the actual video your talking about
