Chorus forms analysis

Hey David, 

I’m currently working on Tongue Blocking Study #3: flutters and pulls. Section 4 is supposed to explain chorus forms but I don’t see a video explaining chorus forms. Section 5 has a video with examples of chorus forms  but there doesn’t seem to be an explanation of them for section 4. I might just be overlooking something but is there a video giving an in depth explanation of the forms?

Thanks, 

Andrew