caskroom/homebrew-cask — pull request #4625 by radeksimko (2014-06-01 15:52:43+00:00)
Title: Make Amazon Previewer cask more generic

Apparently Amazon publishes new versions of their Previewer under the same URL which is then breaking the SHA-checks. I found no way how to download a specific version, so I assume the URL is always giving the latest version.

This should fix the problem.