This video provides a comprehensive understanding of how to post customer and vendor invoices in SAP S/4HANA Financial Accounting (FI). Here are the key points:

1. Posting Customer Invoices: The presenter demonstrates how to post customer invoices.
2. Creating General Ledger Account for Sales Revenue: The presenter creates a General Ledger (GL) account for sales revenue. This account is used to post the sales revenue when a customer invoice is posted.
3. Posting Vendor Invoices: The presenter demonstrates how to post vendor invoices.
4. Creating General Ledger Account for Purchases: The presenter creates a GL account for purchases. This account is used to post the purchases when a vendor invoice is posted.
5. Displaying Customer and Vendor Invoices: The presenter displays the posted customer and vendor invoices. He shows that the invoices are posted in both the customer and vendor ledger accounts and the GL accounts.
6. Reconciliation Account Concept: The presenter explains the reconciliation account concept in SAP. When a payment is received against a customer, it is posted in the customer ledger account and simultaneously in the bank account.

In summary, the video explains how to post customer and vendor invoices, create GL accounts for sales revenue and purchases, and display posted invoices in SAP S/4 HANA Financial Accounting.