We have a site in French and English. But at the moment, the French version is translated in english with Google translate and it obviously dont translate the medias such as images or videos.
So we need to use a plugin such as polylang. This plugin create a version of each page, and translate them automatically, except that we can edit any page specifically (and so we can change the medias there, and put the right video in the right language as well).
It looks like there are hundred of pages, but only 10 or so are used in the site.
I will provide you with the medias (the videos to put in english in certain pages, etc)
So the task is :
1/ To handle polylang to create all the pages and menus for English version
2/ Change the medias when it's necessary (videos...). I provide you with it.
3/ Associate the change switch with the preexisting "FR / EN" link already existing in the site. This should then works with Polylang.