I would propose the unit of "Cuil". 1 Cuil is present when a piece of information causes permanent PTSD in 50% of the people viewing it within 1 week. 0.1 Cuil cause PTSD in 5% of the people viewing it and so forth. Measurements over 2 Cuil express timeframes shorter than 1 Week. So 100 Cuil would cause permanent PTSD symptoms within 8 hours.
Alternatively, you measure how long people remember the video vividly and express the danger as the half life of the information related to it's damage.
Alternatively, you measure how long people remember the video vividly and express the danger as the half life of the information related to it's damage.