In the current hearing he was finally able to explain his motives for leaking information about US military's war crimes in Iraq and other related information. While aggressively pursuing the maximum charge of "aiding and abetting the enemy", for which he could be sentenced to death, the US government has been severely restricting freedom of information about his treatment and coverage of these pre-trial hearings.
...more than two years after their release, the information provided by Manning is used every day by journalists and historians in major publicationsThis article provides the leaked full audio testimony of his statement in the hearing on February 28th. You can also read the unofficial complete transcript provided by his support group, Free Bradley Manning. I recommend this briefer excerpt of his testimony in the following 5:08m video provided by Laura Poitras.
are the world[sic] to enlighten and inform the public, both in the United States and around the world. In a time when the extent and reach of U.S. government secrecy is unprecedented, and there are credible reports that the government has abused its secrecy and classification systems to cover up numerous illegal and unconstitutional activities, Manning’s actions should be seen as an overdue sliver of sunlight into an overly secret system rather than as a basis for a prosecution seeking decades of imprisonment.
See also Daniel Ellsberg's article regarding Manning's testimony from Huffington Post.