I am struggling with getting into extension by looking back on this video. I feel like i am in extension when i get under the bar and unrack it and stand upright with it but when i descend it does not look like i am in hard extension. Also the pain i feel when i brace is a sharp pain around my lumber sacrum area when i take a big breath and squeeze my abs. Its very off putting because its right before im due to descend. Does my back look set correctly and if not a any tips/cues i could try. I heard one cue of "put your shoulder blades in your back pockets" but that makes me think over extension.