pixelate a person’s face

I’m trying to figure out how to isolate (mask) and pixelate a person’s face to hide their identity, without pixelating the entire frame. I just can’t figure out how to do it. Any help would be greatly appreciated.

Isolate the area you need with Splits which creates a separate event. Insert a New Video track above that. Place the cursor on the left edge of the new event and Ctrl drag the original event up to the new track keeping it in sync. It should snap into place. Apply a Cookie Cutter and then a Pixelate filter to the top event. Use a Cookie Cutter circle (or any shape you want) preset and size/position it for the head to pixelate. Use keyframes in the Cookie Cutter to follow the head movement during the event duration.

GG