Criminal has made a post on Theri Teaser... In the above video, the one that's 5mins long the last teaser shown is THERI. It starts from 4mins 40sec.
Promotional clip.. That's how they do it. Infact fans themselves will create long videos to be screened on the big screen editing it themselves.
Here's few examples...
Promotional clip of Vijay's previous films exclusively for fans to promote Puli in the theater... The video includes scenes from Azhagiya Tamizh Magan, Puli audio release function clips, Audience showering huge cut of Vijay with milk clip, Aadi, Vettaikaran, Sura, Kaththi, clip of Vijay's speech in Puli's audio release function, Thalaivaa... in the end Vijay's famous dialogue "I'm waiting" from Kaththi to make the fans go crazy. VIDEO
Best one is this... Vijay's Title Card... Kumutham survey declared Vijay The Next Superstar after Rajinikanth & that video clipping was screened in Ram Cinemas... VIDEO
Promotional clip of Ajith's previous films exclusively for fans used to promote Vedalam in the theater. The video includes scenes from Ajith starrers like Billa, Dheena, Veeram, Mankatha, Citizen, Billa 2, Aarambam, Vaali, Attahasam, Yennai Arindhaal, Vedalam (Aaduma Doluma song teaser) VIDEO