When I watch movies then yes, I rarely browse on my laptop. But sometimes maybe I need to check something real quickly. But for tv episodes and things like that, they don't require my full attention and it's useful when I need to do work also. Anyways, the cloning of the tv screen has nothing to do with the audio, he'll have to change the playback audio manually regardless.

What you can do though is connect the earphone audio to your tv depending on the tv inputs and that way you don't need to use the hdmi audio. Or just buy yourself some cool speakers and connect them to your laptop/pc.