Read Starting Strength. It is important to read it in order to understand what makes a squat, bench or deadlift form safe, and to understand that safe and efficient lift will look different depending of your proportions (ie. it is not necessarily a form error or safety issue if you don't look like platonic idea of a squat form when squatting).
As for video material, in YouTube: "Calgary Barbell", "Juggernaut Training Systems", "Starting Strength".