Dead Bomber posted a video 4 months ago -

Tsarnaev's YouTube page also contains other indications of his interest in Islamic fundamentalism and jihadism. He subscribed two months ago to a channel called "Allah is the One." In recent months, he liked a video with the title "Who wants to become a militiaman?" and a video described as a telephone conversation with a famous sheikh that covers "collaboration" with the Sufis of Chechnya.

http://www.motherjones.com/mojo/2013/04/boston-bombing-suspect-posted-video-al-qaeda-prophecy-youtube