1) The British government have built AI tech capable of identifying extremist views in any video at the incredibly low price of £600000, doing what no other technology company in the world is capable of.
2) A smart consulting company has convinced the British government to waste £600000 on building a model that can flag certain videos from a very specific training set but in real world use is horribly innacurate and completely useless.
My guess: someone enterprising has seen her on TV and spotted a business opportunity. We should be grateful that they only took us for £600k.
I'm sure some other companies could have done it for 100x the cost using "proven technology" (that doesn't work for the problem at hand but sounds nice on paper)
To be honest I actually think if you just look at metadata (IPs, locations, services, usernames, previous uploads, titles, etc.) you can probably get the percentages they are talking about, at least until people start marking up the extremist material in different ways. The article even says they don't want to say how the technology works which implies it'll be trivial to get around.