To me it looks like they used a separate piece of cord for the core. They probably made it continuous(burning the ends together) the cobra braid looks to be just placed on top of it. Put the spliced, or burned part in the center so that it is not visible.
Hope that this helps..
It looks like its about 20 inches of the "cobra" weave. Which means you are going to use 1 foot of paracord for every inch of finished product. I would start with 25 feet, just to be sure. Check out this video I made of the standard cobra. Please forgive me, it was my first video and you can tell. But hey, if you get a laugh out of it or make something cool from it, then I did my job.