[simias]

The rather shallow angle probably helps a lot. On top of that the camera probably has some form of auto white balance which will counteract the tint the CD will give to the image.

Here's a quick proof of concept using a random CD and my phone's camera: https://svkt.org/~simias/up/20200914-000627_psx-cd-reflectio...

Note that the color of the reflection is not much different from a normal picture (visible at the bottom). For added difficulty I used an original PlayStation disc, that's dyed black: https://svkt.org/~simias/up/20200914-000836_psx-cd.jpeg

[jeffbee]

It's very HN that we've been trolled into debating the irrefutable, widely-known, totally obvious fact that a CD reflects light.

[bentpins]

Didn't mean to come across as a troll, this is how I remember CDs, with rainbow diffraction. https://www.google.com/search?tbm=isch&q=cd

[simias]

I think at such shallow angles it's the plastic surface that becomes reflective, not the metal layer with the pits and grooves. Hence the lack of diffraction (and hence why it works with my black PSX disc).

[kevin_thibedeau]

She's using a CD-RW with blue/purple dye. The reflection is definitely coming off the surface.

[Xavdidtheshadow]

Everything reflects light, but not everything reflects it clear enough to read documents through. I haven't held a CD in ages, so it it's possible that folks don't remember exactly how reflective they are. ¯\_(ツ)_/¯

[Someone]

Almost everything reflects light. The discussion is on why it can be used as a mirror.

[gibolt]

The quarter helping to hold down the CD may also contribute by blocking overhead inbound interference.