I don’t much care what anyone calls Xingyiquan, hard, soft, internal, external I just know it hits like a truck and is not as linear as many people believe. As to Xingyiquan backing up, it does, but it attacks as it backs up (that is the goes forward when it backs up), in Xingyiquan attack is attack and attack is defense. I tend to go with my second sifu’s view of Xingyiquan which tends to be “shut up and train”. For some reason I tend to be a lot less tolerant of such discussion when they are about Xingyiquan. Baguazhang, taijiquan I tend to tolerate these much better, I tend to stay out of them, but they don’t bother me. But Xingyiquan to me is Xingyiquan, it is direct, it is not pretty, it is about attack and it has to be trained and it is far from as simple as it appears. Time on such categories is really, IMO, a waste of time when you are talking Xingyiquan.
My thought on this is that you really should not worry about categories like; soft/hard, internal/external, particularly don’t worry about internal/external since it is a false category that has much more to do with a political statement against the Qing government than martial arts.
The only thing I will say I do not agree with is your use of the word limp in the first video....Xingyiquan, is never ever limp. (Neither is Taijiquan or Baguazhang)