Sorry I didn't get back to you til now, but I just got up (it's like 5 in the morning here). OK, my point is that there's more than one Scottish accent, just like there's more than one English accent in the UK. Sure, there are more Scots who speak like the guy in your clip than there are who speak like the kid or Sir Malcolm - but my mum and gran speak more like Rifkind than the guy in your clip (I think it might be a class thing).
But I can't understand why the American woman in your clip had trouble understanding the Scot (I'm sure you understood him perfectly). He was as clear as a bell to me, and most Brits and Aussies would have no problem with his speech. I don't want to offend anyone, but I think Americans are maybe a little too provincial (and maybe a bit lazy) when it comes to anything outside their national borders.
A friend of my mother's who lives in California visited us in the UK, and had trouble understanding players from the Royal Shakespeare Company (who pronounce and articulate RP English perfectly). She is a cultured and travelled lady who is familiar with music and the performing arts - so I dunno why.