The video was taken from the top of the volcano Gunung Batur at sunrise after climbing up the mountain in pitch dark. There were a few streaks of light when I reached the top. By the time the video was taken the clouds on the horizon had been lit up with sun light.
The Kecak is an unusual Balinese dance for a couple of reasons. First, there is no musical accompaniment. The gamelan is not there. Rhythm is provided by a chanting 'monkey' chorus. The polyrhythmic sound of the chanting provides the name, 'Ke-chak'