system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How exactly do movies and tv shows work when an actor or actress starring in them is also the one directing it?

I am referring to major roles, not just cameos. For example Aziz Ansari directed a few episodes of Master Of None and he is the main character.
gpt
In cases where the director is also on-screen, not much is different. Prior to filming a scene, everyone involved will have a meeting to discuss challenges and other talking points. This makes sure everyone is on the same page, everyone understands their blocking, discussing last minute script changes, etc. This little pow wow is standard practice and minimizes reshoots.

One of the biggest differences with an actor-director is that they themselves are going to have twice the work to do, since they have to create and direct a scene, review and approve dailies (all the scenes that get shot over the course of that day), send progress reports to the producers, wrangle the crew and any other 3rd parties involved with the shoot, etc; all while also fulfilling the full time duty of an actor. 

As far as actually directing the scene, directors say and do very little while a scene is filming, since all of the finer points should have been covered prior to slate. Though we see it a lot in Hollywood movies about Hollywood (director storming onto an active set yelling "cut cut cut") this happens very little, as it's a sign that person is not a good communicator, and poor communicators make very poor directors. Most of the time, after discussing the scene and possibly doing a dry rehearsal, the actor will take their place before prepping the crew and then either they or an assistant will call "action" and the scene will start filming.

In the end, it's really just more work for an actor, as now they don't get to stop working/caring once the scene wraps. 

Source: have worked theater, family working in Hollywood.