This video lecture is by SSS Harbhajan Singh Khalsa (Yogi Ji). It was recorded in 1988, and edited with text and images by Guru Trang Singh Khalsa. The original title was "What Sangat Means", and Guru Trang Singh renamed it "The Neuroendocrinology and Electromagnetic Infinity of Siri Guru Granth Sahib Ji" because it contains in-depth explanations ofwhat the Siri Guru Granth Sahib actually is and how it alters our consciousness.
You can watch the original video with the entire searchable transcription here