@ the :02 mark at the start of the video the stock lens on the lower left is shown compared to the 3.97MM lens on the upper right. Notice how the 3.97MM lens reflects the light and appears clear in appearence where its front element meets its mount. The stock lens front element to mount seat is blackened for a very good reason.
I personally would not pay $140 dollars for a lens that can be sourced for less than $50 dollars. When selecting any lens,one must take into consideration how that lens handles light and addresses chromatic abberations. Though I applaud the efforts of the posters of the lens replacement video,I also understand you do not have to strip the camera down that far to replace the lens.