Here's why video editing matters, in two videos.

Earlier this month demonstrators took to the streets in Washington DC to protest against police violence, after a grand jury ruled against prosecuting a white cop who put a black man in an illegal chokehold from which he died.

In footage from the march aired on C-Span, a protester can be heard leading a chant - which the crowd repeats - "We won't stop, we can't stop, until killers cops are in cell blocks".





However, when this footage was featured on WBFF, or Fox45, a Baltimore-based affiliate of Fox News, the report cut away too quickly, with the reporter stating the chant had been "We won't stop, we can't stop, so kill a cop [our emphasis]".





The woman in the video is Tawanda Jones, the sister of Tyrone West, who died in police custody in Baltimore in July last year.

After Ms Jones complained about the editing on Facebook and contacted the station directly, Fox45 apologised to her, blaming an "honest misunderstanding".

The channel also conducted a live interview with Ms Jones later that day.

The protests in Washington DC came days before two police officers were killed in New York by a man who later shot himself.