The video name is "Abwehrkette", so this would translate into something like "defense link/chain", wouldn't it? It certainly looks like a chain more than a sickle. But if there exists a move/positioning pattern in the defense that looks like a sickle, I don't see a problem translating it "defense sickle", or simply "sickle" when it's clear we are talking about defense, not offense.
EDIT: Sorry, I misunderstood that "Abwehrsichel" is a separate move in the video, and not the whole move pattern. There is also "Abwherdreieck", so we talk about the defense positioning types. I guess you can say that the defense chain goes back, than forms a triangle, than forms a sickle, without repeating "defense" all the time.