There is no news about any official website on the internet providing live telecast and webcasting of Thrissur Pooram 2013. But most of television channels in Kerala will be telecasting live the Thrissur Pooram on April 21, 2013. Referred as the Mother of all Poorams, Thrissur Pooram is annually observed in the Malayalam month of Medam (April – May). Poorams are festivals held in Hindu temples in Kerala and the highlights being caparisoned elephants and Panchavadyam – a classical performance of five musical instruments (know more about Thrissur Pooram in this article)
Television Channels Which might Show Pooram Live Online
You can watch Asianet News live here. This channel usually shows Thrissur Pooram live.
Indiavisionlive is one website which has a dedicated website with live streaming of Kerala news. They will be in all probability relaying the live telecast or at least the important events of Thrissur Pooram live. You can also check this link to watch Indiavision live.