The only problem with the USB Flash drive solution is explaining to a 'luddite' where to go into their TV's menus to open up the flash drive. Some TVs detect and open them automatically, others might not. If you can try and find out the TV's make and, if possible, the model - or at least roughly how old it is. And then go Googling for instructions. Videos are great for the technophobes. If you have to use text remember the acronym - KISS.

I faced a similar problem explaining to someone how to set up their Smart TV in order to access a remote PLEX server. She wasn't a luddite (uses a smartphone with all the usual social media apps daily), but nor was she a real technophile. A Youtube video got her on the right path.