In the video (1:40') it says the Karash double loop is supposed to be 'better' than double loop bowline on a bight because there is no 'crossing lines'. What does it mean?
If you start the tying proccess from a well dressed overhand loopknot, you'll probably get a perfect bowline on a bight with no crossing lines (i think Karash is starting from a well dressed figure eight too).
When it comes to life critical applications, one should check the property of redundancy of a double eyeknot, which means that if one of the eyes fails, there has to be the other one as a back up.
if the secondary eye fails (secondary eye=direct continuation of the tail), we would still have the primary bowline eye.
However, if the primary eye (primary eye=direct continuation of the SPart) fails, things might get tricky, one has to check if the remaining secondary bend eye, is strong enough to hold efficiently without failure.
So, in answering this question "which is better", one has to take into consideration, which one of the two has the strongest secondary bend loop, with the hypothesis that both primary eyes of karash double loop, bowline on a bight, would induce failure.