Hey yuan wu, here's what I think is your squatting problem
1. You have a muscular imbalance, your left quadriceps are weaker than your right, and your knees cave in when you rise from the squat. Address that with single leg squats or reduce the weight and correct your form.
2. Your hips aren't tight enough, your weight is moving all over. Your weight isn't on your hips and hamstrings. It's on your knees. Look at your own video and see, you aren't stable. You ARE lowering your hips but I think you break the movement from the knees. I can't exactly explain this on a forum.
3. You're doing a high bar squat, with a ***** pad. What gives? If you're doing a low bar squat, that's still ACCEPTABLE.
4. You "good morning" the weight up like an American powerlifter. Strengthen your back, keep it arched but not hyper-extended.
5. You're not SITTING between your feet. You're doing somewhat of a "box squat with no box". If I ask you to sit, you're going to curve your back..and fall forward.
6. You're trying WAY too hard to keep your knees behind your toes. If you ever want to learn to "sit" in your squat, forget that.
It seems like there's many, but I think it can be corrected, when you learn to "sit" in your squat.
Also I'll actually be coming on Wednesday. I'll be with SydG in the mornings about 10AM, to visit Bkt Jalil to get some information. Then we can chill out anywhere. Just pm me your num