HRW: abuses by the armed Syrian opposition

Human Rights Watch wrote the Syrian National Council and other opposition groups on 20 March an open letter. From it I quote:
 While the protest movement in Syria was overwhelmingly peaceful until September 2011, since then Human Rights Watch has documented apparent crimes and other abuses committed by armed opposition elements. These crimes and abuses include the kidnapping and detention of security force members, individuals identified as members of government-supported militias (referred to locally as shabeeha), and individuals identified as government allies or supporters. They also include the use of torture and the execution of security force members and civilians. Some of the attacks targeting Shias and Alawites appear to be motivated by sectarianism.  (emphasis added by me)
Following the creation of the SNC Military Bureau on March 1, 2012, to liaise with, unify, and supervise armed opposition groups including the Free Syrian Army (FSA), Human Rights Watch calls on the Bureau to condemn and forbid these abuses in order to achieve its objective of ensuring members of the armed opposition comply with international humanitarian law and to meet its human rights obligations. Human Rights Watch also calls on members of the armed opposition that are not under the operational command of the SNC to desist from committing these rights abuses.
 Human Rights watch gives a few examples. One of them is is a vido of the hanging of what appears to be a member of the shabeeha on 22 January by the Kfar Takharim battalion of the Free Syrian Army. .