[hohloma]

He is trying to fly using "ridge lift". This is one way to get lift when for example paragliding. If you google paragliding and soaring there's tons of info. The lift is often a bit away from the ridge edge and works up to twice the height of the ridge (at least what I remember from paragliding lessons). Also see wikipedia - https://en.wikipedia.org/wiki/Ridge_lift

[powerbroker]

As a former hang glider pilot, I agree. One of the downsides to turning parallel the ridge, too soon, is that the wind closer to the ridge is slower, while that away from the ridge is faster. This can lead to a tendency for a glider of 13-15 m wingspans to tend to 'turn into the hill'.