Counterarguments can be one of the most confusing parts of an argumentative essay, but this video called "How to write a counterargument" does a great job of explaining why they are important and how to write them.
"How to write a counterargument" by mistersato411 is licensed under a Standard YouTube License.
The Harvard Writing Center provides a great overview of counterarguments, too. I encourage you to read this website for more information: Counterargument.