The FBI has already made a very public case against The Tsarnaev brothers by releasing the videos of them walking with the backpacks, and then a grainy photo of Dzhokhar without the backpack. According to several media outlets, there is an unreleased video that shows them dropping the backpacks and walking away.
If the FBI found it acceptable to release the other video which certainly raises suspicion about the brothers, if not publicly implicating them of the crime, then why do they find it justifiable not to release the one truly condemning piece of evidence they have? It is deceitful for them to release suspicious videos, but no hard evidence. They have caused a media uproar with no basis. As an American, I feel we are owed the truth, no matter how hard or "chilling" it is to watch.