Appears to be in open G tuning, GDGB maybe?. Basic three chords appear to be the open G unfretted, A full barre on the second fret, C full barre on the 5th fret. He plays a stopped rhythm using that open G chord, then later does a descending C (5th fret) to A (2nd fret) slide move. I think. Of course he is adding a few single slide notes, and it's difficult to tell what frets he's actually playing because his fingerboard has all those stickers or paint blobs on them, but this should give you the general idea. Try it and see if it sounds somewhat like the vid.
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Seems to me Shane Speal had a lesson - at least in regards to the tuning.