Rav Schachter discusses Rashi on Daf 39b what the safek of the gemara is, incorporating netziv's explanation of the two types of pidyon ma'aser shayni. Also, Rav Schachter noted the definition of hava'as makom given by Rav Menachem Zemba and said that towards the end of Tosafos on daf 38a in d"h oh dilma assumes it. He also said that there are a lot of commentaries regarding a tosafos on daf 40b...