Even though the lecture cited examples, I would sleep easier knowing validations were done to mitigate risk. Even if there were no changes affecting the human factors of the device, you still need to check the product. What if there are no changes but suddenly an outside factor such as out of control bioburden affects your product? The validations are there to help you mitigate these and other factors. Besides, its good business practice as it does build a foundation for new experiments later on or, in the eyes of an auditor, allows you to boast the robustness of your quality plan/risk mitigation.