This is a shiur given by my brother-in-law, R’ Shlomo Berkowitz. He discusses the machlokes between the Ritva and Raavad in Succah 11b about whether hidur mitzvah is d’oraisa or derabbanon. This shiur was given at the Phoenix Community Kollel for Yeshiva bein hazmanim of chol u’moed Succos.