The video is going with 6 years, I'm going to tell you if they are 5 years or older you are playing with fire. The manufactures dont want an experation date, but they stop warranty at 4 to 6 years depending on manufacturer. Go figure.
On a related note, just so you know. If you purchase used tires(even takeoffs) you have no warranty from the manufacturer. They only cover the original purchaser, on the vehicle they were purchased for. This is why so many reputable tire shops dont sell used tires. All responsibility goes back to the dealer that sold the used tire.