User Manual LG 65SM8500PLA 65“ NanoCell 4K TV

The C1 series sold in the US has a black back cover.
However, some other markets will have white so it's
possible that any unboxing videos you've seen were done
in other markets, where a white version will be sold.

'Can be wall mounted' should mean that the tv comes with
an attachable stand but you could wall mount it instead if
you get yourself a wall mount, while 'wall mount' suggests
that the tv does not come with any stand. This tv does
come with the wide solid stand shown.

Don"t think it's fixed should be alright if you don't leave it on
the same screen for a long time.