The examples that are shipped as part of the DiffLib repository requires LINQPad to run, a free tool made by the author of C# 4.0 in a Nutshell, a O'Reilly book about C# 4.0, LINQ and various other topics.
Note that you need LINQPad version 4.27.1 or higher.
Ensure that you load up the solution file in Visual Studio 2010 or above and do a full rebuild for the Debug target before testing any of the examples. They rely on the binary produced as part of the build output.