I don't want to keep editing that post, so I'm going to start a new one.
The question you've shied away from is exactly HOW you differentiate between metaphor and literal truth, when the subject discussed is so far away from anyone's experience.
I have not shied away from that question at all, but have answered it clearly in posts 26 and 30.
You did, but I think we need something a little bit more descriptive (and objective) than:
2) When two Christians differ on their interpretations, how do you determine who (if either) has it right?
The same way I would approach any disagreemnt: by looking at the arguments presented by each side, evaluating those arguments, studying the relevant background information, and applying logic.
And there's the rub, as has been pointed out. You may want to consider these questions....
1) How do you know how to correctly interpret Jesus' words?
I don't claim to have a completely correct understanding of everything Jesus said, but some examples, including the relevant ones from this video, are quite straightforward and I interpret them as I'd interpret everything else. Every day I have scores of conversations, read several books or articles, watch TV, and listen to the radio. As I do so I encounter figurative language all the time and I interpret it using common sense.
Your "common sense" may not be "common sense" to others. After all, you acknowledge that there are other Christians who interpret things differently than you do. And my "logic" and "common sense" tells me that the bible is nothing but a bunch of fictional tales created by ignorant people. Does stating just that satisfy you? If it doesn't, why should anything you state here satisfy us? Nothing you've said here is constructive to answer the question HOW to interpret the bible correctly.
Assuming that you're a defender of the video, the question can be turned around. The video's entire case is based on the assumption that Jesus meant each of the quoted phrases to be taken literally, and based on this claims that Jesus was "crazy" and "insane". Lose that ridiculous interpretation of Jesus' words and the whole video falls apart and looks rather pathetic. So how exactly do you, on behalf of the video maker, know how to correctly interpret Jesus' words?
Surely, the burden of proof is not on us to show that when someone says "cut off your hand" he doesn't mean "cut off your hand", but he means "deal with your inner demons without actually cutting off your hand, sinner!"? Or any of the other dozens if not hundreds if not thousands of interpretations one can think of when they apply their "common sense" or whatever? Where is your evidence that this particular interpretation is "ridiculous" and that your interpretation is the correct one?
Was the great flood, practically genocide, a metaphor? Or do you really believe that god literally drowned/killed nearly every single human being because they became "wicked" and didn't appreciate your/their god? Is hell, where non believers suffer for eternity for the severe crime of not believing in this particular god, a metaphor? "Cutting off your hand" from a book with such similar atrocities in it doesn't sound that far fetched to me, actually.
I'm looking for someone who can explain why I should take such a video seriously, but it doesn't seem like anyone wants to do so.
You don't have to take this video seriously. Just like you don't take some/many of the other interpretations/denominations of Christianity seriously. And, unfortunately, much like how you can't explain to us why we should take your interpretation or even Christianity itself seriously. But you just do (take one specific interpretation and just run with it), so why can't the creator of the video take one interpretation and run with it as well?
Are Christians generally taught to preempt every talk with religious aspects with "First things first: I just want to say that I am of x denomination and I don't interpret the bible the same way you do. In fact, I think that some of the things you believe about god and Jesus are at best inaccurate and at worst ridiculous. So whenever I refer to Christians, Christianity, God and Jesus, I usually mean my interpretation of them, not yours, which I don't acknowledge as correct"? If they don't, why do you expect the creator of this video to do so? Especially when the burden of proof is on you? And you've failed to provide any kind of evidence to show that your interpretation is accurate?
Oh, and welcome to the forum

It's high time we have some fresh blood spilled around here!*
*Metaphorically, of course!