SikhNet user asks the question: "How is the kachhera considered to be on, even while you are changing it, being on one leg? Why is it that some sikhs believe that all 5 kakkars have to be on the body, even while consummating their marriage (having sex)? Where is the practicality in that?"
In the video Guruka Singh describes how this can be a very personal thing and depends on what your relationship is between the Kakkars and yourself, and becoming conscious about why you wear the kakars.
About Kacheras: https://www.sikhiwiki.org/index.php/Kachera