I love that clip.
and the part before it where he's getting ready and talking to the crowd
http://au.youtube.com/watch?v=Eh44QPT1mPE
so... IEI? the type that seems to dominate amongst great songwriter-musicians
He's INXp--but yeah, that was already pretty evident, I guess.
You're right--a lot of his songs seem to deal with typical Fi subject matter, (I'm thinking of the song 'Harvest' right now... Very good album, overall.)
Based on these interviews, it's REALLY tough to tell INFp/INTp... In trying to get an answer, I'm comparing his personality to Bob Dylan's (who is prob a Gamma introvert, IMO,) and then to Kurt Cobain's (who is INFp, IMO...) I'd say, from these two clips, Young's personality seems closer to Cobain's than Dylan's...