Craft:
There are plenty of places to buy hidden cameras over the counter. (Just put 'spy camera' into Google).
I don't necessarily think that the video is totally false, however editing and commentary can make a great deal of difference. For example, in 1984 I watched a report on BBC TV on the miners' dispute. The commentary made it clear that our brave police were suffering intolerable abuse and injuries at the hands of miners who had no respect for the law. At the end of that week I watched exactly the SAME footage in Australia (on ABC). The commentary made it clear that the UK was effectively a fascist state where the police were totally out of control and continually used brutality to oppress peace-loving strikers.
My point is that a different (less biased?) reporter might use exactly the same footage of those scenes in Paris to show how French Muslims are currently unable to worship together in a mosque of sufficient size, why they find the need to employ private security in order to protect worshippers from Islamophobes, and the measures they take to ensure that the rights of local citizens are protected.