the whole "only queer actors should take queer parts" issue
John Early put it best: straight actors should play gay characters because it's hot
But seriously, I find it odd that anyone thinks that gay cis characters should only be played by gay actors. As long as gay actors also play straight characters, which they can and have done for the entire history of the performing arts, then why does it matter? Generally I'd say it's more important to have queer stories that are written/directed by queer people. If those queer writers and directors are comfortable with casting straight actors in their work then that's cool. If they think a queer actor is better suited for that particular project then that's cool too.
Of course it's quite a different issue when it comes to trans characters, as openly trans actors have historically not been given opportunities in the film/TV industry. There certainly isn't much precedent for openly trans actors playing cis roles in the same way that gay actors have played straight roles. But I think that is starting to change, and we will see more trans actors taking on roles that are not necessarily trans (really the majority of characters in media are not even explicitly stated to be cis or trans, if it's not relevant to the story). For the present time I think it makes sense that most trans characters should be played by trans actors but there's still some grey area. Are there times when it might make sense to cast a cis actor for a trans character, especially if the character is closeted/pre-transition? Yeah maybe, if it's handled respectfully and there are trans people working on the project behind the scenes.
[sorry I haven't seen Sarah Z's video yet so I dunno if these same points were brought up. I'll watch it later]