In reply to deepsoup:
The rope used in the D2 splice looks like the nearest to a kernmantle rope.
But, watching the video*, the core is braided (looks like a 12-strand braid). So the splice relies on the braiding closing up and locking the splice.
The core of a kernmantle rope isn't braided; it's just a bunch of strands.
Again, the caveat that I've never done this...
* there are a couple of places where the technique shown looks a bit odd; pulling the mantle back in, I'd have opened the other mantle up, to loosen it. Pulling on the entire rope would cause everything to tighten up, so I'm not surprised he struggled to get the mantle to pull through. And, when doing the final trim, again, I'd have loosened the surrounding mantle, pulled the excess end out, trimmed it, and then pulled the surrounding mantle tight again, so that the trimmed end would be pulled inside the outer, and the outer braiding would close up nicely around the inner.