How do I start playing the video here:
https://watch.plex.tv/show/sex-in-strange-places/season/1/episode/1
Plex is not an illegal streaming service. They have some (free, ad-supported) content available on the base site, but they don’t have everything.
Plex also serves as a kind of metadata service for content they don’t own (sort of like IMDB). What you linked to is a show that is not available on Plex’s own service. Looking around, it does not appear that any streaming service Plex knows about has that show available to stream (see bottom left):
Plex does not know about all the services, but as this is a BBC documentary, you might want to look at them. Does the BBC have a streaming service?
