He doesn't seem like a man of integrity, but I guess the sample of his work (the one video I watched for five minutes) is pretty small to make such a judgment.
I agree, but hopefully our judgement will be proved wrong.

I
really want to see the debate happen, I reckon it would make for great listening. Without a doubt, it really would be really entertaining. Plus, the guy's ignorance annoys me, he needs educating.

I do think you're correct about the krugmandebate thing...he can pretend to be "above it," but the fact is, it's for a "good cause" and he looks like every bit the "fake" of a "nobel prize winning economist" to dodge it.
You're spot on. I think the fact that this would be on a smaller scale makes it much more effective. That is to say, Paul Krugman can hide behind his stature - he can be forgiven by his supporters for ignoring it much more easily because he has 'bigger fish to fry' (not from our perspective of course). For the Murphy-Krugman initiative, the amount of pledges has to reach a considerable amount for it to gain traction. The pledged sum has to be sizeable enough to match the profile of Krugman - only then would the media, the general public and thus Krugman himself take interest.
Sam Seder has no such recourse. The scope of the libertarian grassroots is powerful enough for us to publicise the initiative to a high enough proportion of his liberal audience to cause him discomfort at the fact his cowardice is preventing money going to the poor. I have no doubt that this would really catch on in libertarian circles. Let's just say libertarians won't take to kindly to those videos posted above and would be motivated to make sure that his empty challenge blows up in his face.
Don't forget to take into account the fact that Sam Seder's fans would also want to see this debate go ahead for the same reason as us - we as listeners want entertainment. They'll be as confident in their Sams's ability to defeat FTL (and would want to see happen) just as much as we want to see FTL defeat him.
Furthermore, Sam Seder cannot plea ignorance about it since he knows (and in fairness checked out) the idea:
http://twitter.com/#/SamSeder/status/170618310000513024 To conclude, I think this is extremely workable. All FTL need to do is accept the challenge and invite Sam Seder to appear on FTL. If he accepts the invite, then happy days. We all have a quality episode to look forward to. Hopefully, the debate would live up to it's potential, which I'm sure it will as FTL hasn't dissapointed yet, and would go viral (and therefore exposing FTL to a huge number of libertarians) which can only be a good thing for the show's future.
And if Sam Seder rejects, then well, it'll probably be the biggest mistake the guy ever makes in his career.