Honestly, you're going to be hard pressed to find their music. I searched for a while, gave up and finally bought several of theirs CDs on eBay back in 2002.
Whoever uploaded this video actually spelled the band name wrong. It's spelled Yamaarashi, and this song is also called Yamaarashi. I believe the two albums it appears on are their self-titled, and their 1997-2001 Single Collection.