I confirmed searching for "Iran" with a before set ends up showing me all recent results. BUT if i use this search form to generate the query (and not the youtube search bar) it works.

via the search form: https://www.youtube.com/results?search_query=+%22iran%22+bef...

via the YT search: https://www.youtube.com/results?search_query=+%22iran%22+bef...