Computer audio (e.g. a video playing) is included when you tick Share audio in the picker.
Keeps storage inside the $5/month block. You can change this per video in the Library.
3-second countdown, then it records. Click Stop here or Chrome's Stop sharing bar to finish.
Keep this tab open. Everything is also saved locally as it records, so a crash won't lose the take.
Uploading in resumable chunks. You can keep working in another tab.