For the record, anyone who reads this probably shouldn't even go to that link. Any and all minecraft mods can be found via the official forums.
That aside, there are several reasons why a mod will cause your client to crash.
- You didn't delete Meta-INF
- You don't have a listed pre-requisite to the mod already installed.
- You have a mod that conflicts with the one you're trying to install
- Your mods is not up to date with your Minecraft client version.
And there are a menagerie of other possibilities.
But, THAT aside, we're not a mod troubleshooting forum. You'd be better off asking the developer on his main website, or via his Minecraft forums post.