Is there a better way to hide TV shows from the gallery?
The solution to that is pretty easy: Instead of renaming the folder to .Video (and thus "hiding" it completely), simply place a file named .nomedia inside it. That way you hide it from the media scanner – while the directory stays visible in your file managers.

I cannot check with FB (refusing those data collectors), but apps usually depend on the "media provider" for such activities as you described. The "media provider" uses a database, so available media can be found quickly (if each app would scan your entire storage on a "share" action, that would take far too long). By placing a .nomedia file inside a directory, you tell its scanner to skip that directory (and all its content including subdirectories) from being included with this database.