Surveillance video from inside Marathon Sports on Boyston Street was shown at the trial of Boston Marathon bomber Dzhokar Tsarnaev on Wednesday as part of the testimony by store manager Shane O'Hara. In the video, staff and patrons can be seen reacting to the blast, treating the wounded and using clothes as makeshift tourniquets.The Boston Marathon bombings on April 15, 2013 killed 3 and injured 260. Tsarnaev, 21, faces the death penalty and 30 charges in relation to the attack.