Fix a black screen when recording Chrome

A black recording usually means Chrome shared a surface the GPU or OS will not paint into the capture stream. The fix is almost always a different source or a fresh picker session.

Fixes to try

1. Stop, then record a tab instead of the full screen (or the reverse).
2. Disable hardware acceleration in Chrome settings and retry once as a test.
3. On Windows, update the GPU driver if black frames appear only on full-screen shares.
4. Close other capture tools that may lock the display.
5. Confirm you selected the monitor that actually shows the UI.

More context: when Chrome cannot share a surface.