Bava Batra 96 - September 29, 26 Elul

Rav Yosef brings a braita to clarify whether we hold that wine that is turning to vinegar one should say borei pri hagafen or shehakol. However, the braita had several interpretations and it was therefore unclear which opinion Rav Yosef was trying to prove from the braita.   If one purchases wine and it goes bad soon after, is the seller responsible to give the buyer new wine? What is the halakha regarding wine that was made from the leftover grapes that had already been used for making wine - is it considered wine or not?