Jerk causing vibration and Y layer shift... Bad stepper?
Your video doesn’t show a printer moving terribly fast, which makes it seem like it could be a problem with the motion or the electronics. Check the movement of the Y axis by hand, is it smooth? With the belt on, and the stepper motor attached, you’ll feel some resistance and little bumps, from the steps in the motor, but it should be pretty smooth, and especially it should be consistent across the range the bed can move. If you take the belt off, the motion should be like butter. Check the belt pulley isn’t slipping on the motor shaft. Check the idler on the other end of the belt spins freely.
The motor could be suspect, the driver could be suspect. Try running the printer so it sends the bed back and forth, and push against it with your hand a little as it moves. It should be pretty strong, and shouldn’t skip steps from some light pressure. If it does skip easily, it’s something with the motor or driver, or possibly the wiring to the motor (I had a failing connection on my extruder stepper that manifested as wimpy torque and skipped steps). You can beep the wire with a multimeter, and wiggle it around as you beep in case it is a loose/flaky connection. I’m not sure if the creality printers have trimpots for the motor drivers, but some drivers have a bias adjustment where you adjust a voltage with a multimeter, to decide how much current the motor gets. It’s not usually something that goes out of adjustment.
If it doesn’t skip steps easily from adding some resistance with your hand, then it might be an incorrect jerk setting on the printer, or the slicer travel speed is too fast, or, the hot end is hitting some plastic that is sticking up (an overhang curled up possibly), and skipping a step there maybe.