The footage will be spun into a three-minute TV ad due to air on Friday night in the first ad break after 10pm on over 80 commercial channels, including ITV1, Channel 4 and Sky.
The three-minute ad, "Welcome back", will launch simultaneously on YouTube, Facebook and Twitter. Media planning and buying is by MediaCom.
An estimated 35,000 passengers coming through arrivals today are being greeted by a crowd of around 300 people who are bursting into synchronised song and dance.
The specially compiled list of songs includes 'I am the passenger' by Iggy Pop and 'I knew you were waiting (for me)' by George Michael and Aretha Franklin.
The crowd includes a "vocal orchestra" - vocalists using their voices to recreate the sound of instruments including guitars, violins, cello, flutes and drums.
Eighteen hidden cameras are being used to film the action.
The ad is a follow-up to previous Saatchi & Saatchi ads for T-Mobile, including "Dance" filmed at Liverpool Street train station and "Sing-along", filmed in Trafalgar Square.