Privacy

I didn't read into the specifics of the IR LED they are using, but assuming it's somewhere in the 850-900nm wavelength with sufficient power, they should be blocking you out if the CCTV is recording infrared images.

There's a video here that explains the principle. I've highlighted the key part, but feel free to check out the whole thing to understand the idea: https://youtu.be/fywvB4Unjv4?t=240

Thing is, if the camera records in the regular, visible spectrum only, it will see you just the way you are. Most cameras automatically switch to IR mode when the environmental light strength drops below a certain threshold, so you'd be "invisible" at night, but clear as day during, well, daytime.

If you're talking about normal video surveillance, I think most of today's cameras use regular light. These sunglasses would be effective against a biometric scanner, the iPhones depth camera, a Windows Hello screen unlock or an XBox Kinect. But the average camera on the street uses visible light and likely has an IR filter in place (at daytime), so it won't even see infrared.

What works against these are ski masks, wearing a motorcycle helmet.... Or even large hat or golf hat, depending on the camera's perspective.