One of your employees, boasting about masturbating in a NSPCC toilet whilst at work. Then uploading the video - "Amateur Fetish Porn at Childrens Charity premises"
Is that seriously what the video was called?
Holy shit 
Having a private weekend kink is one thing but if it rules your life to the extent you bring it to the workplace that's something else altogether.
Definitely gross misconduct. Then times that by 1000 if you work for the NSPCC.