I have never personally used the butterfly swords before, but i can see how they will help with wing chun mechanics

I have, however, done a LOT of FMA knife sparring, and from an edged weapons perspective, you guys are WAYY too close to each other.

cool vid though, i'd love to see a guy with a bo staff spar with a guy with the butterfly swords, it will up your butterfly sword game immediately because the Bo staff occupies centerline, and you have to get around it and inside it, we did this in my jkd sessions with knives verses staff, difficult to say the least.