If you notice that that video is aimed at a certain type of person,primarily a black,hoodies from working-class backgrounds and not white british youths.Although some have carried guns.
The shootings and massacres,involving the use of legally-held weapons,were held in the areas that you would least expect.Those whackos that committed the worst examples of these,occured out in small country towns,typical of the
British greenbelt.The type of locations that you would see in Inspector Morse,Miss Marple and in Midsomer Murders.
Those who committed those awful massacres,were men who had regular jobs and paid their way in society,earning an honest income.
Middle-class people or lower-middle class people,are primarily the majority of target-shooters in the UK.
Would those types of punks go to the extent of allowing the cops to screen them for background checks and inspection of their premises? I think not.
Also they could rob gun stores,but the cops would eventually get them,dead or alive.