So you're coming from the TT and not so more from the tapered headset. I see what you mean now, but I see no hump in it but a TT in a curve shape like form. If it is bent it is more weight as the TT needs to be longer to be able to go from A to B, so you are right in this, but the weight penalty should be minimal in terms of weight/ratio. About the stand over height, it looks as if you were right on this one too, but I don't think this is affecting the ST length in terms of size/length (16.5"/419.1mm for small, 18"/457.2mm for medium and 19.5"/495.3mm for large). As the TT starts its arc right from the ST, it looks as if the fitting was a bit too tight when standing with your feet on the ground, but, on the other hand, I can see how low the TT has been fitted onto the ST, which thing, I believe, makes a call for the gusseted stack bit in it. I can see what you mean now, but I am not all too sure whether I fully agree with you anyway.

Well, it says on the video doesn't it? They call it "tapered" because of the way it's been made. I cannot see what you mean when you say this design decreases stand over height, but it has been made in this fashion with purpose. The idea is to strengthen the frame in those parts where it is more likely to suffer from unwanted stress. In the second video the guy says they wanted to come up with an usual looks a little bit different from what Transition costumers are used to, but as you can see there is also a technical reason for it. And not only Trek does it (Trek Scratch, Remedy for instance) but look at Spesh and what they've come up with for the next season (Trail SX, etc.).

The bike looks quite nimble and it has beautifull angles. I can see it ain't very comfortable for climbing (Tyler struggles a bit to keep the front end down) but you could have a Talas fitted for that purpose. There is a chance I am going to put this bike down on my shopping list. BTW, I did enjoy Tyler's video: I can tell he had a good time doing it.