please follow the video on Module 3, it should work,
You need to create a folder called Lib, copy the jar, then add the path to the jar under properties , add the java build path and add the jar.
The hadoop jar is provided in the one of the files.
On windows X you have to go tp Project > Properties > Java Build Path > Libraries > Add External Jars
In Eclipse you have to add the all the jars that are from hadoop.mapred.* packages. Please right click on the project -> properties ->Java Build path -> Libraries Tab -> Add external jars and add the following
/usr/lib/hadoop - add hadoop-annotations.jar,hadoop-auth.jar,hadoop-common.jar
/usr/lib/hadoop/client - Add all jars
/usr/lib/hadoop/lib - Add all jars.
Once these jars are added, Eclipse will recognize the MapReduce programs