Not forgetting a metric without defined units beyond a percentage and a wishy-washy phrase about video quality & buffering.
At the end of the day, if the network can offer more than sufficient speed to serve a video, the buffering shouldn't be an issue as the s/w should be able to work far enough ahead. At the application layer, there's usually some rate adaptation stuff built into the s/w to optimise what the user sees based on the end-to-end connection characteristics.