Reps 3 and 4: your hips moved backwards out of the hole. It was hard to see your back angle with the clothing you had on but you look like you rounded at that point. Maybe try…
-Focus on pushing your back up into the bar as much as driving the legs/hips
-I know I may be raked over the coals by some guys in here but…gasp…strengthen your core to better handle those loads.
-Reducing weight/number of reps as rep 1 and 2 looked good. I mean it wasn’t horrific breakdown on 3 and 4 but it wasn’t crisp either. Sometimes it’s tough to know how hard to push. Without challenging yourself you won’t make progress but constantly using bad form aint great either.
One thing I can say for sure: bring workout clothes to the gym.