Understanding complex analysis - the study of functions of a complex variable - is important because we're exploring the Riemann Zeta function extended into the complex plane.
The following are three youtube playlists which I have found to be high quality and accessible.
1. Open University M332
This course from the UK's amazing Open University programme is simply excellent:
2. Richard E Borcherd's Undergraduate Course on Complex Analysis
Richard E Borcherds is a leading mathematician (Fields Medal winner) and knows his subject. This combined with a gentle narrative helps us understand the subject better, not just be exposed to lots of facts.
3. Petra Bonfert-Taylor's Analysis of a Complex Kind
Petra Bonfert-Taylor is an accomplished German mathematician specialising in complex analysis. Her very friendly approach, one which empathises with the newcomer or learning student, is particularly valuable.
