I would guess there is photocell next to the LED and comparing the amount of light to the ambient light the cameras get. They might also be doing something clever and using the LED itself as a photo diode.
It's actually not that hard to use LEDs in this way. I think it's not done a lot because in applications that need a light sensor, a purpose-built light sensor works a whole lot better, and it's rare that space is such a premium that having one is an issue.
Glasses may be a use case where space is at a premium, though, so it could make sense there.
It looks like the connector just happens to fit so it's only being used to make the electrical connection. The 4 pins are actually power, ground and I2C data and clock.
This looks almost identical (though maybe a bit more stripped down, haven't looked closely) to the Orange Pi Zero which has been on sale for a few years at a similar price.
I'm kind of curious, what would this do which actually requires GB ethernet? Seems like processing limits and SD card speed would get overwhelmed quickly.
Does this have enough HP to work as a caching proxy or mini firewall?
If you're not already familiar with Soft White Underbelly (interviews and portraits of the human condition), I highly recommend checking out Mark's other videos. I particularly enjoyed the recent series of folks from Appalachia.
I've been really happy with a similar Cannon printer (Cannon G3200).
The print quality is quite good, it comes with an insane amount of ink, and you literally buy full replacement bottles of ink and pour them in the tanks.
No artificial page limits, no checks for non-oem ink.
