Tellybox Shop... 
And another episode begins

Well, that has escalated quickly... 

And is it all wonderful?
Splendid! 
Took the USB stick with non-working videos back to the shop, tried it on every size of Series 7 Samsung and no go.
Tried it on the Samsung Series 6 and worked fine.
Tried it on LG, Sony, etc. and all worked fine.
The sales guy reckoned the LG 2018 model was the best evah but I liked the Samsung stand design so took the (obsolete) Series 6... works perfick. 

It's very poor by Samsung imho, if the tele I'm watching now goes kaput they're not exactly going to be the only brand I look at. I rarely use the USB video option but i always want to know I could
Do you know which formats they've killed off support for?
I had a problem with a selection of .avi and .mkv files... both I understand are 'containers' which can hold various formats of video and codecs...
So I'm not sure if they have 'killed off' anything or if the Series 7 firmware is a bit immature and needs an update... either way I am sorted now! 
Given the popularity of both formats I can't see Samsung arbitrarily killing off support for them. I'd be more inclined to believe that the firmware needs updating.
Yep
Container formats, I have to ask why? They just cause confusion while affecting to simplify
Test team lead to erk: “have you tested.avi?” Erk: “yes”. So they close down testing and release the product having achieved sod all
Precisely...
And similar will repeat at the shop
Average Customer: "the TV won't play my .avi video"
Shop "let's test it with our .avi file" (different contained format)
Shop: "look it works fine, must be your files, do fuck off sir"
And most would fall for it and slink away shaking their heads
(Google suggests the big problem is actually .mkv files)