Rav Mordechai Friedman starts this 50 minute halakha class with a discussion about Shabbat Zachor – and answers why we remember Amelek before Purim and how can we fulfill this obligation.
He then continues to discuss Purim, the mitzvot, their blessings and meaning.

This shiur is reposted with permission from the VBM—The Israel Koschitzky Virtual Beit Midrash of Yeshivat Har Etzion, where you can find both audio and text shiurim regarding all aspects to Purim.