These exercises are great for training you to keep your hips/pelvis raised for longer but there's still the issue of how to raise the pelvis/hips in the first place. I noticed that in my forward bend there's still a degree of curving of my back. It used to be terrible and it took a lot of work in pushing back in Downward dog and really trying to stick my backside out that I managed to reduce it. It's better, but still there and I'm attempting to raise from there rather than just my hips and I think that may be what's holding me back.
In the press to handstand, the first video, I try to reduce that even further by almost arching my back and it's that I think that made the difference in helping me get my hips up, quite way to go on this but I think I might be on to something.