– Yes there is stress on your psoas and hip flexors but I'm not sure where you heard that trunk flexion doesn't work the abdominals? Next time you're in the gym give that exercise a try and let me know where it burns most.

– You're going to work your hip flexors in a lot of abs exercises, it's just a matter of where those muscles are and what they support.

– Stabilization and anti-rotation exercises are great and might put up another video soon with those in there, but old-fashion decline sit-ups are still a great way to build your abs.

– As far as squats, deadlifts, military presses etc… I think they're great for your core but you need to add in some exercises that focus more on the abs to get the best results you can get, treat them like any other muscle and resistance. (I love farmer's walks, great exercise)

thanks for the comment, hope this helped,

Chad