You said you had the chords. What chords are you using? The tune is in the key of G#m. That's a very unusual key to play such a simple tune in. I believe that he has his guitar tuned up two steps (four frets) higher than standard. These are the reasons I think that is likely. First, it appears to be a short-scale or 3/4 size guitar having a short neck. They're frequently tuned up higher four or five frets. Second, while it's hard to tell for sure, it doesn't appear that he's using any barre-chords, which would be necessary to play in the key of G#m on a standard-tuned (EADGBE) guitar. He seems to be playing the chords too easily to be holding barre-chords. Also in the extremely brief very beginning of the video he appears to be using open strings. I'm not positive, but I think this is the case. You wouldn't want to tune a full-sized guitar up that high, but if you put a capo on the fourth fret it would be the same thing (Now, with the capo, open strings being G#C#F#BD#G#). Then the tune could be played "as if" in Em, which would be much simpler. The beginning nine seconds of single-notes would also then be easy to play, (now, with the capo on the fourth-fret) starting with: second-string open x2; second-string third-fret; second-string first-fret; second-string open; third-string second-fret x2, etc, etc. Try that. It should then be much easier.
And welcome to Guitar Zone.