This play along jamtrack has a longer intro which bilds up other five measures. Start playing the major 9th arpeggio exercises after the guitar scratches and you will be able to play the entire piece as demonstrated in the video. The notation at the top of the page is taken from the Jamtracks PDF and shows the double bass part. Its melodic line and the various string parts indicate the key of C# minor. As this key is the relative minor to A major (they share the same key signature), the A maj 9th arpeggio fits the C# minor tonality nicely and lends it a heroic quality.
This composition is inspired by Manuel Göttsching's pioneering masterpiece E2-E4. His album has been released in 1984 and consists of a minimalistic, hour-long electronic track that Göttsching recorded in one take using a sequencer, improvised keyboards, metallic percussion, and guitar soloing. Highly recommended!