AD says I must go through them to have warranty work done

[Tri-Tip]

If they are not charging you anything extra for this "extended warranty", you don't have to worry about it unless you have an issue during the 3rd, 4th, or 5th year, then you can decide if you give it to the AD to have it fixed (no charge), or deal with it on your own.

As someone said above, it would only cover manufacturing defects, which is unlikely during that time period, I would expect that if there were defects, they would show in the first 2 years.