Recordings are saved in whichever format your browser can encode — WebM in Chrome, Edge, and Firefox, MP4 in Safari. Both play in most modern video players.
No. Everything happens in your browser. Your screen recording is never sent to any server.
When you choose to share a browser tab, system audio from that tab can be captured. Sharing an entire screen may not include system audio depending on your browser and OS.
Enabling the microphone lets you add voice narration on top of your screen recording, useful for tutorials and walkthroughs.