I have taken half a dozen or so flights with Norwegian and rated them quite highly. Last month I flew OSL to.AES and the WiFi was a welcome distraction as I had forgotten my book.
Being over 6ft seat pitch is everything to me and having done LGW to OSL once with Norwegian I will be considering them every time now that BA is enhancing away the only thing that stopped my knees rubbing against the seat in front. Quite simply, if there are no exit seats available there's no need for me to book with BA without considering Norwegian when flying to OSL.
As for price, I have definitely snaffled a £39 Norwegian fare at some point. I remember being delighted! The cheapest BA ET return I have seen (and paid) is £99 return. Both were booked months in advance.
I look forward to seeing the videos when I am on a suitable device.