Exist this adapter for phones?

[thedicemaster]

it's possible, but not for amateurs.
there are USB-based capture "cards" that act like a webcam, which could work over an OTG cable if you manage to write a webcam driver for your device as well as a camera app capable of switching to a 3rd camera.

if you're really lucky, some older chinese tablets may already have some generic webcam drivers which would allow you to view ps2/vcr/dvd/older consoles in any camera app.