::That edit was quick attempt to show you why your edit was unbalanced. Here is more preferable variant: 
 :::On 9 September two European hostages who claim to had been held captive by the opposition were released, said that they had overheard their captors saying that the Assad government hasn't used any gas in Ghouta. The hostages, claim to overheard the Skype conversation through door, described it as a Skype conversation, between three individuals, one of whom had identified himself as FSA general. However, the hostages didn't "know who these people were or if they are reliable", or if the conversation was "based on real events or on rumors", additionally no official details have been released on who was holding them or how they were released. 
 ::I removed most undue detail about this incident like their time spent in captivity. I even removed their names, since they are not making expert opinion, though I put "European hostages". Added "claim" before "held by opposition" because there is "no official details...on who was holding them"(a statement which I added at the bottom). Removed the opposition provocation part, which I couldn't find in the source provided and added their reservations as direct quotes to avoid vagueness.