Rabbi Avrohom Baruch Zachariash teaches the halachas of Chol Hamoed with the Mishnah Berurah (O.C. 537:15 & 16).
0:45 Cutting a field on Chol Hamoed.
1:09 Water and gas pumped to upper floors of an apartment building.
13:00 Cutting your own grain rather than buying in the store.
18:09 Picking grapes because your gentile neighbor is picking his.