Kevin, just took a look at both your video and the eBay pics. Judging by the shot of the neck in your video at the ~15 second mark, and also by one of the pics on eBay, your shamisen would seem to be a chuuzao/jiuta one, even tho’ the vendor called it a nagauta instrument. (The chuuzao sao comes to an “edge” very near the box, as does the Tsugaru one, whereas a nagauta neck has a gradual, rounded “slope” towards the neck instead (see nagauta neck pic here - http://thumbnail.image.rakuten.co.jp/@0_mall/i-a-b-m/cabinet/00771998/img55956186.jpg). Your shamisen seems to have come with a nagauta bachi. As for the koma, it doesn’t seem to be a jiuta one, and also don’t think it’s a nagauta one, but I can’t see the koma clearly enough to say more than that…
Re: the skin, it does look synthetic, but neither the eBay pics nor your video was a clear enough shot to say for sure. It is definitely not cat. If your skin were natural/dog, you should be able to see some areas where the dog’s hair had been removed, although you won’t necessarily see that all over the entire skin. With synthetic skin, you won’t see any such marks - it’ll be “smooth”, or at least uniform, as Kyle said.
By the way, in your video, it looks like you’re playing left-handed - yes? Just curious.