Occasional Shiurim about the Jewish Festivals:
Machine Matzot 
Chumra and Pesach – A Meta-halachic Analysis
Pesach: Matza and Celiac Issues
Pesach: The Kezayit – A Halachic Biography
Drinking on Purim
Purim – When Was the Torah REALLY Given?
Chanukah – The Downtown Chanukiah
You can also watch this shiur on video at https://www.ou.org/torah/machshava/halacha-hashkafa-contemporary-society/downtown-chanukiah/
Chanukah – An Electric Festival?
Chanukah – Greek Wisdom and the Inner Light
Click here to hear a short Chinuch podcast on Chanukah on the website TheFamousAbba.com
Pesach – Selling Chametz – Torah Mitzvah or Legal Loophole?
Pesach – Korban Pesach Today – Hashkafic Dream or Halachic Nightmare?
Pesach – The Structure of the Hagadah (with 2 source sheets)
Second Day Yom Tov for Visitors to Israel
Saying Hallel on Yom Ha’atzmaut (updated 2016)
Yom Ha’atzmaut – Capturing the Essence of the Day
Teshuva – The Rambam on Hilchot Teshuva – Chapter 1
Selichot – Balancing Ahavah and Yirah s
Yom Kippur – Simcha or Affliction?
Shmini Atzeret – Simchat Torah – Climax, Simcha and a Taste of the Next World
Tisha B’Av 2017 – The Dangers of Machloket LeShem Shamayim
Tisha B’Av – Mourning in a World of Rebuilding
Tisha B’Av – Learning to be Mourners
Tisha B’Av – Building Redemption Through Exile