The video discusses back pain stemming from intervertebral disc degeneration (theymanam), explaining that the spinal discs lack direct blood circulation, which prevents them from self-repairing and makes them vulnerable to damage, especially from prolonged sitting, obesity, and smoking, which restrict the flow of nutrients. The primary symptom is localized back pain that worsens after sitting or standing for long periods but does not typically radiate to the legs in the early stages.