Thanks Blake. Although my squat numbers are pretty weak (170kg BS and 155kg FS) the problem it's not about standing up. It's more about getting down... I feel lack of stability. As for the back, maybe this video was not the best example because I was a bit tired that day and the filming angle was not the best one, because I have a pretty good deadlift (about 240kg and 280kg for partial rep) and I do sets of 3/4/5 reps of pullups with 50+ kgs hanging by my waist. So I would say my back is pretty strong.
About the hips I thinks you're right... I'll work that.