IB 2.4 – Proteins in 13m from Dan Rott:
Many assessment statements are also covered by Stephanie Castle (with more being added all the time).
What is a Protein? – a 7m video
Some past paper questions answered by IB Blueprint: Carbohydrates, lipids & proteins – Past Exam Paper 1 Questions; Carbohydrates, lipids & proteins – Paper 2 Questions.