The translation of Egyptian hieroglyphs was made possible by the discovery of the Rosetta Stone. This artifact features an inscription in three scripts: Ancient Egyptian hieroglyphs, Demotic (the common writing system of Egypt), and Ancient Greek. By comparing these texts, scholars were able to unlock the meanings of the hieroglyphs and the other languages.
However, it's important to recognize that these translations are not entirely precise. The exact pronunciation and reading of the ancient Egyptian language remain uncertain, and many interpretations presented in videos are based on educated guesses and inferences.