Pundits ridiculed Tesla Motors (TSLA -0.67%) last week after its "$500 a month" new-car loan program turned out to be based on some dubious assumptions. But Tesla might end up having the last laugh after all. In this video, Fool analyst John Rosevear explains what the real goal of Tesla's new financing offer might be -- and why it's a great long-range move for the upstart carmaker.