The campaign is the latest instalment in the government's long-running drugs awareness and information initiative Frank.
It was produced on behalf of the Home Office, Department of Health and Department for Children, Schools and Families.
The agency has produced 10 separate films that will be seeded across a range of websites popular with young people including Weebls Stuff, Burst Media, Bebo, MySpace, You Tube and Faceparty. Online ads will also run on media sites such as Channel4.com.
One of the most eye-catching of the films imitates a David Attenborough wildlife documentary, along with a voiceover impersonating the presenter's imitable speaking voice.
Attenborough himself was approached, but when he declined to take part in the ad, he gave his blessing for an impersonator to be used.
The ad reveals the ups and down of a teenage house party, where some are having a great time, but others are suffering problems caused by the drugs they have taken.
You can view the ad .
The campaign was managed through the Central Office of Information, with media planning and buying handled by i-Level.
Chris Janzen, client services director at Profero, said: "This campaign marks another significant step forward in how Frank relates to and engages with teenagers in its communications. The reality and honesty of the creative will undoubtedly have a positive impact and influence on the audience."
A spokesperson for Frank said: "Profero have continued to make the online Frank brand relevant and engaging to our youth audience. Through a mixture of advertising formats, especially the creative use of branded content, our online presence will help to prevent drug use among 11- to 18-year-olds."