KG's video was helpful although a bit windy for my tastes. Here's the simple approach: 1.) If you want good barre chords, you MUST incorporate them in your DAILY practice; 2.)practice proper position as shown in KG's video with the index finger only (omitting your thumb): 3.) Practice several positions on the fretboard noting the differences needed for good tone: 4.)Finally, practice the barre with thumb and index finger. Caution: once your hand feels pain, relax your hand and restart when it feels rested. That's it. In 6 months of everyday practice, you'll have respectable barre chords. Playing again . . . Rognvald P.S. Remember, everyone's hands, arms, and body are different. Sometimes, your most effective position may not be 100% theoretically correct although you should strive for the proper position as a goal.
"And those who were seen dancing were thought to be insane by those who could not hear the music." Friedrich Nietzsche, Thus Spake Zarathustra