[TeMPOraL]

That would only maybe work for automated tracking; if someone wants to get the image of your face, they should be able to do it in post, unless the recording quality is shitty - the tiny variations in brightness might contain just enough information to reconstruct the face shape with a little filtering.

(Now I wonder, how narrow-band such IR LED is, and if it could be made to emit a single frequency so sharp, it would create funny diffraction patterns off cameras' surfaces and lens imperfections, clobbering the high-frequency components of the image...)