Interesting video Daz, good find.
I can understand why people question whether they are worth the expense, but in my opinion they definitely are. And not just in the snow.
I find traction, cornering grip and braking distances all to be noticeably improved in frosty and damp, cold weather. The softer rubber also means they're quieter too.
The £1k 'investment' certainly seems a lot, no denying that. Also storing 4 wheels with tyres when not in use can be a pain if you don't have much space. But as has been said, the costs aren't that great once you've psychologically got over the initial outlay. They should last easily three winters, possibly four. And some of the cost of the wheels can be recovered by resale. Tyres are a consumable, they wear out and eventually need replacing. You need to have four of them on the car at all times anyway, so they may as well be tyres that are best suited to the conditions you're driving in. You can then save your summer tyres for.....summer!
And if you still struggle to justify it, look at some of the items you may have ticked on the options list, and ask yourself how many of them will help keep you out of a ditch when winter does its worst.
Are they absolutely essential? Possibly not. Could I manage without them? Probably, if I had to. But I don't want to just manage. Once you've tried them the benefits are clear, and the costs aren't as great as you may think. So for me it's money well spent.