Rabbi Avrohom Baruch Zachariash teaches the halachas of the Three Weeks with the Mishnah Berurah (O.C. 551).

0::30 Can a father eat meat if he is attending his son’s bris via ZOOM during the 9 days
07:10 Ponevezh Yeshiva said the Bris Seuda was more important than the Bris Ritual
09:42 When does the obligation “Chachnasas Choson” begin?
10:48 Different seudas mitzvos fulfill different purposes
12:24 The Rav never had a Seudas Bar Mitzvah
13:30 Can you have a Bar Mitzvah seuda before turning 13?
15:40 Should one wash at a seudas mitzvah?
17:19 Working on Erev Tisha B’Av
21:00 552:5 Seuda Mafsekes – Egg
24:25 552:6 Bread and water
29:50 Saying a pasuk after chalitza with a shoe in her hand
32:45 Avoid sitting directly on the ground
37:00 552:9 Eat enough to make it through the fast, but if you can eat less then you are a “kodesh”.