Google Video has looooooong videos, and sure enough, someone already posted the entire film in its entirety.
The venerable Archive.org has it in a downloadable version, for those of you who wish to migrate it somewhere else.
Wonderfully enough, they also have the story (in Japanese) by Ryunosuke Akutagawa. A chap has translated it into English here.
The remake is also great...
The Outrage
With Paul Newman as a Mexican Mifune
Shatner.... as... a.... minister
Edward G. Robinson as a swindler
Laurence Harvey (Domino's Dad!) as the objectively conflicted husband
NOT ON DVD - why?!?!