This shiur explores the opening sugya of Chullin: who is permitted to perform shechitah (ritual slaughter), whether the allowance is lechatchilah (from the outset) or only bedieved (after the fact), and discusses the status of a tamei (ritually impure person) in both chullin and kodshim contexts.
https://www.torahrecordings.com/tlamud/005_seder_kodshim/003/002b