Your deadlift video doesn't really give much information; but from what I can see, your hips are starting too low and your upper back is not tight enough. Definitely re-read the Deadlift chapter on Starting Strength and focus better on setting up.
The squats that the fellow in your video is performing are really bad. It is a high-bar squat; he is wearing the wrong shoes; he is dive-bombing much too quickly into the bottom of the squat, thus bypassing his stretch reflex and not really allowing him to keep tight lumbar and thoracic extension. Your squats should NEVER look like that.
Form is most certainly the problem here, not flexibility. Have you finished re-reading Starting Strength, or have you just started?