TED Ed -- The Nature of Light
Kurtzgesagt -- What is Light?
Crash Course Physics -- Light is Waves
Cosmos -- The Speed of Light
TED Ed -- Light-Seconds, Light-Years, Light-Centuries: How to Measure Extreme Distances
Crash Course Astronomy -- Light
Prof Dave -- What is Light? Maxwell and the E-M Spectrum
Crash Course Anatomy -- Vision
TED Ed -- Light Waves, Visible and Invisible
TED Ed -- How We See Color
NIH -- The Visual System: How the Eye Works
TED Ed -- Why is Glass Transparent?
The Curious Engineer -- Why is the Sky Blue and Not Violet?
Crash Course Astronomy -- Telescopes
Crash Course Physics -- Geometric Optics
BozemanScience -- Emission and Absorption Spectra
Crash Course Astronomy -- Stars