Wow, I tried routing prowalk and other videos to my 4k TV with youtube app and it is stunning. Didn't try this earlier because I thought I would have to leave my google password sitting in the TV, but they allow me as anonymous for free. For some reason I can run 4k at double speed that would cause jerkiness on my laptop, which helps for instance on a 6 hour video walk thru Jerusalem. Sitting really close gives great immediacy as if folks might bump into you, altho I have to reduce over vividness with TV settings.
Some really good vids to look for are Hadrian's Villa and also the Appian Way. I didn't find great ones, but will post a teaser that lets you imagine how good an Appia Antica one could be if they would just walk or bike continuously without a lot of chit chat: