Su Dong Chen: Entering Method

Here's a nice way of setting up what Tai Chi Chuan calls "parting wild horses mane".
Su Dong Chen has a very eclectic version of Internal Martial Arts, and this looks a lot like some of the entries Tim Cartmell teaches also.
The problem many Tai Chi guys have is being nearly completely immobile. I think it comes from too much fixed step (stationary) push hands, where opponents stay rooted and try to off balance each other.
I recently had some e-mails from "Bob", who asked how to neutralize gut punches from his son while they are doing some light sparring. Bob does Yang Tai Chi Chuan and push hands.
I encouraged him to bring his extended guard in closer as the opponent closes, to slip and cover rather than reach out to parry when the opponent is in hitting range.
This is non-traditional for an art like Tai Chi Chuan, but we gotta' use what works.
The second bit of advice relates to what I mentioned above: Don't get stuck in a root. Move evasively and root when you hit.
Likewise, as Su Dong Chen demonstrates above, "Call to get a response" - that is open with a hand attack to get the desired response from your attacker.
The projection Chen does on the student is actually more like the Xingyi "Rooster announces the dawn", where "parting wild horses mane" rotates the opponent over your lead leg/thigh. The entry principle is the same.
It is also like "Slant Flying", but I believe slant flying usually has your arm above the opponent's arm rather than below.