I'm not in Greece yet, but from watching the video it looks like you each time you see a bird (raven, crow, owl) you should read what they say and follow it. That often involves switching to a different color pathway.
There is / are:
1 owl screen - "follow the color of the mask of Agamemnon" - I don't know what color that is
3 crow screens:
- follow the color of amethyst - purple
- follow the color of envy - green
- follow the color of rage - red
3 raven screens: ( eagle ? ) - large black upright bird with yellow beak
- follow the color of Poseidon's home - blue
- follow the color of the river of Acheron - I don't know what color that is
- follow the color of burned out forge - grey - THIS LEADS TO THE END OF QUEST LOCATION
This list isn't intended to indicate what order the birds appear in. I couldn't figure that out from the video.