Your back is immediately coming out of extension, simultaneously with your knees extending without moving the bar. The bar looks like it's a little far forward, and so your hips are artificially low. Move your ankles a little closer, so your hips are at about the point they "end up" at the beginning of these reps. Make sure that your hips DO NOT MOVE between the point where your shins touch the bar and the bar leaves the floor. The "push the floor away" cue will help here.
The bench press is OK but your elbows are a little bit lateral: try a slightly lower touch point. Think of "bringing your sternum up" to the bar when you lower it, rather than letting the bar come down, and pack your elbows in as tight as you can.