It's common to hit PRs as you go along a cycle and still be able to push yourself for the next couple of days or weeks. But at some point where your body can't continue to grind through and PR on a daily basis. When you do push yourself beyond the prescribed intensity on a regular basis, you'll hit a wall and it may take some time to recover from all of that physical stress.
Jumping sideways could be from some sort of asymmetry that you have. For example, one leg may have been a little more fatigued than the other so you weren't finishing all the way with both sides; or you may have had an early arm bend with only one arm. Considering you we're just on a strength cycle and you were feeling terrible, you may just not have been finishing all the way with your legs and dropping it forward.
Your technique looks pretty solid. You whip your head back on the extension and I think that's why you missed that 90 but you seem to handle it fine so if it continues to work for you then that's not a huge issue. Also, you look a little wobbly overhead. Make sure you're keeping your back tight when receiving the bar. If this becomes an issue as you go up in weight then I suggest doing some Snatch Push Presses (behind the neck, of course) to strengthen that position.
Other than that, good lifting!