For this shot, club golfers are generally most concerned with getting the ball over the lip of the bunker, when in fact, this should be the least of our worries.
The upslope is giving us added loft to the shot so upwards is not the issue. Getting the ball to go forward enough to reach the hole is more of a problem.
As with any upslope, we need to adjust our body positioning so that the ball is forward of its normal position and the shoulders are somewhat leaning with the slope. This will mean that nearly all your weight will be planted on the lower foot.
When the slope is as steep as this one, the main aim is to keep as stable as possible and keep your sternum in the same place. That makes this a very arms and wrist dominated action as you see with David in the video. The weight stays completely still and entirely planted on the low foot.
Be mindful not to fall backwards as this will have you hit too far behind the ball and lose speed.
This is not a feature as much as a standard bunker shot so don't worry about having the face too open. As David mentions in the video, the aim is to play these more like a plugged lie by swinging hard into the sand just behind the ball and leaving the club low and short in the follow through.
The big mental challenge with this one is to appreciate that there is plenty of loft to get the ball up and out. If you have any anxiety about 'lifting' the ball then you will end up leaning backwards and hitting too far behind.