Check the first two or three minutes of this spinal cord operation. Before the dura is opened you can see the csf  (and cord?) moving through the membrane (around 0.30 plus). When the dura and then arachnoid is opened the flow of csf is clearly visible (around 2.10 to 3.00 plus)

This is a view of the exposed thoracic spinal cord with an abnormal vessel. As the surgeon cuts the abnormal vessel, you can see the pulsing of csf around the cord.

(Thanks to Ciara Dhiomasaigh, biodynamic craniosacral therapist in Galway, for the latter video)