This guy knows his shit. Deadlifts are HIP DOMINANT. Think about driving the living shit out of your heels into the ground and ‘FUCKING’ the bar (srs). Try and incorporate a regular stretching routine somewhere for your hip flexors.
Other points. Keep the bar close to your body as you pull. Feet roughly hip-width apart. Your arms are merely hooks; never let them become slack at any point in the movement (hello bicep tear). Good lower back arch.
Personally strongly disagree with retracting your shoulder blades as somebody else said. Not only does this severely limit the amount of weight you can pull, but for me it feels like the lower back is called upon to take on alot more load to make up for weak positioning where the lats and traps can’t do their job properly.
Oh, and please, please, please avoid high reps with deads. 5-6 at the MAXIMUM. Focus on quality reps and weight progression. Form subconsciously goes to shit as fatigue sets in, and believe me, this movement isn’t exactly forgiving for slacking of form with heavy loads.