Your Tai Chi looks like Tai Chi to me. But I am uniformed, so my opinion on it really doesn't mean anything.
What I've said in the past is that SD doesn't flow like CMA. I'll revise that. The Northen sets I've seen do not flow like Northern sets should.
Here is an example of what I mean.
This guy is
NOT an SD player, but his form is performed much like I have seen SD folks peform in online videos (and at AAU Nationals in Dallas):
http://youtube.com/watch?v=f48lAjfJLek
Too much power and snap for a long fist form, and not enough continuous flow.
This is a much better example of the same form:
http://youtube.com/watch?v=h7_syGd3S0o
SD Northern forms have all the right movements (for the most part). No doubt about that. But The Northern "flavor" just isn't there in the stuff I've seen. SD Northern sets are performed just like SD Southern sets. Long Fist sets are supposed to exhibit relaxed power, not hard jing.