It's basically the old 'raise your hands, palm up and inhale; lower your hands, palm down, exhale'. But it's not a formal salute. He's really just using it as an exercise. A lot of my younger shidi don't really get the breath coordination thing at all yet. They're young. They can do it all in one breath, totally unlike me now. I'll pant like a overheated dog if I don't reset my qi with that movement. But I still use the namaste bow because that's just my style.
That's my implied point in all this. We can study the minutiae of the forms, but ultimately, there's variation within each lineage, so it's really muddled research. Of course, now we have youtube and can make some comparisons. But those youtube vids are just snapshots. I've someone was to take a snapshot of Yan Fei's class, they might get the wrong impression. He might be doing something different than his master taught him in an effort to transmit a lesson. I do something different than what Yan Fei teaches me because I've had different input. Decheng does something different than this Suyun bow, possibly because he was connected to the Wushuguan for so many years and they probably standardized all of that for unity of their performances. It's tricky research, and in the end, might have no real meaning whatsoever.
Don't get me wrong. I don't say that to discourage you in this research. In fact, I really enjoy reading it here. But in a typical Buddhist fashion, I wouldn't get to attached to it.