This is now making the rounds through media in the United Kingdom. From The Daily Mail:
The video is believed to have been filmed somewhere inside Syria, where ISIS control a swathe of territory, including Raqqa, the capital of the terrorists’ self-proclaimed caliphate.
The origin of the video is unclear. The Mirror in the UK says:
The video, which has been circulated online by a Yemen-based anti-ISIS activist, shows the children bound and forced to lie face down in a line. …The veracity of the video has not been confirmed, but the terror group’s slick propaganda team is known to film their barbaric executions and circulate them. Islamic State is also known to have executed children in the past.
But is it legit? The Independent now says no. Evidently, that video is not what people think it is:
A video purporting to show Isis militants murdering hundreds of Syrian children was actually filmed more than a year ago as propaganda for the terror organisation. The clip was allegedly filmed after the Islamic terror organisation seized a Syrian government airbase, Tabqa, outside Raqqa in Syria, in August last year and allegedly shows the execution of 250 Syrian soldiers, not children. Charlie Winter, a senior researcher at the Quilliam Foundation, told The Independent the clip “definitely, definitely” did not show children being executed and labelled some reporting of the video as “incredibly irresponsible.” “In a conflict like this where we need complete clarity, not putting this video in the correct context can be incredibly harmful,” Mr Winter said.