Q. How do I do an in-text citation in APA when there is no author?

First of all, make sure there really is no author. Even if you are citing a film or a YouTube video, there is a director or person who posted the media, so do your due diligence and make sure the item you are referencing is indeed "anonymous" or without a known author. Also make sure you have formed a proper citation for this item on your reference list FIRST. Once you have a proper citation you will know that whatever comes in the first position of that reference is what needs to appear in your in-text citation. In addition to this, with APA the way you cite something in the text depends upon whether you have put a "signal phrase" in the sentence. For more about that see https://owl.english.purdue.edu/owl/resource/560/02/