This song is styled after Al Momaday's retelling of the myth of the twins (in the book "The Way to Rainy Mountain"). Here's a quick guide to the meaning of various points in the song, which revolve around the same theme:

0:00 - Child in tree; redbird flys down.
0:17 - Child climbs up after bird (and tree grows taller).
0:20 - Bird = Sun. "I've been watching you for a long time..". They have a son.
0:40 - Girl gets lonely.
0:50 - .. so she decides to dig up the root and rope down to earth.
1:00 - .. but it doesn't reach. And the Sun comes home.
1:10 - He can't find the girl, then sees her on the rope. Angry he is.
1:30 - Sun tells ring to traverse the wire and kill the girl.
1:47 - ..and it does. The son is now all alone.
2:11 - Time passes. Once he is able to, the son heads down to earth.
2:21 - He meets grandmother spider. Though he was told not to, he throws the ring up in the air, which hits him as it lands and..
2:41 - ..he splits in two -- a twin. Later, the twins throw the rings into the sky...
3:01 - ..and chase them over a hill.
3:12 - They come to a cave where the giant lives. He tries to smoke them to death...
3:30 - ..but they repeat the words "above my eyes" as they remembered and the smoke rises.
3:52 - The giant sees this; afraid, they let the twins go.
4:03 - They later see a great snake..
4:10 - ..and kill it.
4:20 - They tell grandmother spider about this, and find out that they had just killed their grandfather.
4:40 - The grandmother dies from this, but the twins live on as heroes.
5:27 - FIN