This moving niggun is known by the name “pilpul”, which usually refers to a deep analysis and debate in Gemara. In Sefer Haniggunim it explains why:
“The niggun is built in a question-answer format. What the first refrain demands and questions, the following refrain answers, justifies and settles. The following refrains climb and ascend, dismantle and build, challenge and respond, in a similar pattern to that of a pilpul in Gemara.”