The channel, the first of its kind to roll out in the UK, gives customers access to 72 minutes of content a day on subjects such as sport, music and news, which is continually updated throughout the day.
Content includes footage from MTV, Sky Sports, the DJ Pete Tong and the Barclaycard Premiership. Each clip will last no longer than eight minutes, in line with mobile viewing habits, which have been determined through research.
"Today on 3 represents the culmination of a year's experience of how our customers interact with our services - every day we learn more about what our customers enjoy and how and when they want to use our video content," Gareth Jones, the chief operating officer of 3, said.
The promotional video features a woman presenter who explains what viewers can expect from the service. It demonstrates the broadcast quality of the service with clips of music videos, football matches and news from ITN.
The promotional video will be sent to all 3 users next week and will mark the full-scale launch of the service.
Mike Cornwell, the chief executive of TBWA\GGT, said: "It's so exciting to be in right at the start of a new medium. It combines the best of relevant personal communication with the power of broadcast."
The ad was art directed by Pete Jones, and written by Anthony Abdool.
The director was Trevor Leighton through Fix Digital.