^^^Well certainly not a 155 pounds
. I think there have been discussions of some sort of weight limit where after that you should use a belt. I honestly would think that would be up to the individual and the circumstances.
Topshelf I watched the vids another couple of times because I know you want me to give you
something to work on (which I think is really a good way to think). And I did notice that you seem to initiate the movement by breaking at the knees first. It's hard to tell but I actually think I detected you knees actually bending before your hips a couple times. That could be the source of your sense that your knees are coming too forward.
Concentrate on breaking at the hips first while lowering the bar. If you break at the hips and go down the knees will follow naturally. If they didn't you would lean/fall forward or at best would be doing a good morning
.
Some people like to call this "sitting back into it" so if that helps think of it that way. Although for me I think that creates more confusion because it leads to this belief that you should be striving to keep the back straight up and down. The weight should be over the middle of the feet so make sure it is not being transferred to the front of the feet. Drive up straight throught the heels/middle of the feet but don't think about pushing on the floor or really too much about the legs at all. Think instead about moving the bar upwards. Start with pushing the shoulders into the bar and try to relate to the barbell instead of the floor. Just think about moving it up as hard and fast as possible.
That's about all I can think of at this time.