The footage was broadcast by Sky News yesterday evening.
The person in question, Simon Beard, was employed by the NYA as a development officer until last September and subsequently as a consultant from November. He was Criminal Records Bureau (CRB) checked as recently as 18 November when he became a consultant.
Among his responsibilities, Beard delivered a two-day training programme called "R U Ready", advising youth workers how to counsel young people about sexual relationships.
NYA chief executive Fiona Blacke has issued a statement in response to the Sky News report: "All staff and associates undergo a full disclosure CRB check prior to employment or contract agreement and we are continually reviewing and improving our safeguarding policies," she said.
"In relation to Mr Beard's employment with us we are certain that all the necessary checks and procedures were applied.
"We were dismayed, therefore, to learn of the allegations relating to Mr Beard broadcast by Sky News. Because we take any potential threat to the safeguarding of young people so seriously as details emerge we will scrupulously examine our own policies to see if there is anything that needs to be done to strengthen them."
Beard has also written occasional book reviews for Children & Young People Now and comment pieces in the NYA pages of the magazine over the past few years. We have decided to delete these contributions from our website archive, pending the police investigation.