I think it is rather ingenious Just download fixed blocks (say 64 Kb) in backward order for the 2nd node...

The only thing here is that this "ease of segmented downloads" will work for only two nodes. If you add an additional node, you'll have to do the calculations again (how far is node 1 and 2, where in the middle do I start with this 3rd one?). But overall, since download speeds could fluctuate a lot during the file transfer, this is an easy way if the developer doesn't want to do some calculations, etc.