I am in the same "boat" as Malc, as I do not have a warranty as I run older cars. There is a heart-in-your-mouth feeling when you read on the forum about what has been done under warranty and the cost!
The video kept stopping for me but I hope you are correct Herbie - that would be a good outcome!
Can you "capture" a sample of the fluid? See what it looks like / feels like?
Anything like this is a worry. I would get the service done at Lexus - get them to diagnose the issue and cost and then consider an independent if it is going to be very expensive.
I presume you have always had your car serviced by Lexus?
I good independent locksmith will programme you one much cheaper than Lexus c.£150. Unfortunately you live the other side of the country, otherwise I could recommend a good one in Kent.
Looks like you have made your decision - hope it works out for you. Personally I need to fit a roof boot, but I will not be buying a car with a pan roof just to be on the safe side.
I believe the consensus of opinion is that it is not advisable to fit roof bars to a car with a Pan roof. Some have but by all accounts I would not do it - hence I would not buy a RX or NX with a pan roof. Just my opinion others may differ.
I wonder if Lexus will give you a good trade-in price?
Many years ago a local Taxi firm ran Mitsubishi Carismas. Mitsubishi bought some for quality control purposes at a VERY good price considering the mileage!