#1: Bar appears too far forward at the start. Can't really see hwere you're putting the bar because your video hides your feet. Read THIS.
#2: You are doing what we call "standing up off the floor" - which means that, with the bar on the fllor you are trying to lift it off the floor by extending your hips, or "standing up." Don't do that. The initial motion off the floor is KNEE EXTENSION. Push the middle of your foot straight down into the floor.
Work on those and then post another video.