1) Andrew Goodwin's music video theory outlines 5 key aspects: lyrics and video matching or contradicting to create meaning; beat and video synchronizing to engage viewers; genre conventions; artist promotion; and voyeurism.
2) Music videos like "Salt" by Bad Suns match lyrics and video scenes to reinforce the song's meaning while "Paralyzed" by Mystery Skulls syncs the beat to a basketball's bouncing.
3) Genres have styles - alternative videos use nonsensical images interpreted differently while rock videos typically feature live performances.