Auto-blur will automatically pick up faces without you needing to select anyone. Currently Identity Cloak covers 90-95% of faces.
On some occasions you may find that people's faces aren't being picked up by Identity Cloak's auto face recognition. Identity Cloak identifies faces of being 50+ pixels/ full facial features. On some occasions you may have part of someones face from their profile which is also less than 50 pixels (depending on the quality of the cameras the recording has come from) which means their faces aren't being picked up. You will need to go in and manually redact these faces.
We are currently working on improving this to 95-98% of faces being recognised in our next release.