The default for anything you are doing rather than saying. Screen fills the stage; only the kicker, the lesson index and the mark ride on top. Use it the moment your hands matter more than your face — clicking through Setup, running a query, watching a deploy. Your voice carries the teaching, so the frame does not need you in it.

Screen-share teaching with a face on it. Camera bottom-right at 17–20% of frame width, one corner for the whole lesson — moving it costs the viewer a re-scan every time. Park it over dead space, never over the org's left nav or the record you are about to edit. If the corner you need is busy, switch to scene 03 rather than shuffling the camera around.

When the screen is narrow and you are explaining, not demonstrating. The camera gets a real column instead of a corner, with room under it for the point you are making. Nothing overlaps, so both the screen and your face keep full contrast. Costs you screen width — only worth it when the shared window is a form, a record, or anything else that does not need 16:9.

Any procedure longer than three steps. The rail lists them in the mono 01/02/03 voice the whole platform uses, with the current one at full ink and the rest dimmed. It is the cheapest possible fix for the most common lesson complaint — “I lost track of where we were.” Update it as you cross each boundary, or take it off screen.

For the debug log, the error toast, the one field that matters. Zoom in post, not live — a mid-recording zoom reflows the page and loses the viewer. The small locator keeps the crop honest by showing where it came from; without it a zoomed frame is a claim the viewer cannot check. Come back out as soon as the detail is read.