Overall conclusion of my time practicing with David: I want more! Respect and thanks to David and Joy for sharing their resources and providing this fantastic time of learning for us.
David spend some time getting into uddiyana bandha and explaining how it can be better developed and accessed. One way to develop more awareness for uddiyana bandha is to practice the uddiyana kriya before asana practice or just after headstand. (See here for uddiyana kriya practice) David kept mentioning that it is very beneficial to practice uddiyana kriya daily.
Then, downward dog is a perfect pose to access uddiyana, especially when bending the knees. And, all inversions accentuate uddyiana (so next time in halasana - bring the awareness to uddiyana, don't forget to set up the pose first, engaging thighs and legs, inwardly rotating the thighs and lifting through the buttocks)
Concentration / Pacing during practice
David explained that such observations are very informative about one's approach. It's good when you notice that you are doing this (loosing focus, pacing, softening the practice, etc.). Don't go about it punishing yourself for your limitations in the practice, e.g. "taking is a bit easy here and there" BUT notice your reaction when you observe that your limitations. Investigate whether you can accept and live with these limitations or whether you want to change them. If you want to change those limitations, you need to ask yourself what you can do to change the situation. May be you need to change your intention, commitment, perception, something in your life, or may be something else.