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Students' test cut first. I provided the miao dao they used, which was super sharp (good for tatami) but couldn't withstand hard-plastic bottles cutting without the edge rolling, not to mention hitting pork bone. Nevertheless, here they are:

http://www.youtube.com/watch?v=I8LgtdnQt8Q
Taku, first used his Paul Chen side sword that was sharpened to withstand cutting hard objects (battle-sharp). Then he switched to the Miao dao and everything goes.

http://www.youtube.com/watch?v=8Bcic4Wmpro
http://www.youtube.com/watch?v=GM_8IOFK-5Q
http://www.youtube.com/watch?v=vFDkxX3Blzw

http://www.youtube.com/watch?v=CxTkN9Yixag
His katana was cold steel 88k that was very sharp, and the Chinese jian was only battle-sharp, then katana again.

http://www.youtube.com/watch?v=7kQqlfIcup8
Dung used his battle-sharp huanuo willow leaf sword. His vertical cut later switched to the miao dao.

http://www.youtube.com/watch?v=I4FxaTaRMF8
http://www.youtube.com/watch?v=RH_WOUM0J9I
http://www.youtube.com/watch?v=93w87TEYD00
These were my entry level student. The swords they used were good for tatami.

My friends' test cut videos:
http://www.youtube.com/watch?v=Em0wPrTYB1U
His katana was sharp for tatami.

http://www.youtube.com/watch?v=VPOFVa9QIVo
His huge bagua sword was totally blunt. Then he switched to a tatami-sharp katana.

http://www.youtube.com/watch?v=zmHqGLGY0vA
My friend's ching dao was battle-sharp. Then he switched to the super-sharp Miao dao.

And finally, my video of test cut.
http://www.youtube.com/watch?v=PIj_PD0BrfM
Deva Slayer was a battle sword, thus it was not meant to be tatami-sharp. I included EVERY failure in the video for reference. :) And the last vertical cut, I did it with the super sharp miao dao..... it cut into the dry double roll mat beneath the 3 mats I severed. It shows how important sharpness meant to tatami cutting. However, cutting pork arm and newspapers roll were not so sensitive on sharpness. Even the blunt bagua dao sword had cut newspapers roll successfully before. Pork arm and newspapers roll, on the other hand, required a lot more power generation and blade alignment then sharpness than tatami cutting (as one can see how well Taku did with the miao dao, while he couldn't cut newspapers rolls as good), which I value more for being realistic to historical battle usage.

Here is the blade of Deva Slayer. Note the appleseed edge by the distortion of light reflection.
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And here is the blade of the miao dao. Note the rolled edge from cutting plastic bottles.
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