KMPlayer/VLC are Win32 apps and are not doing you any favors when it comes to battery life, Modern UI apps are designed for mobile environments. Preventing the screen from turning off when not in use will also impact your battery. Also you refreshed your machine mid-stream in your testing so that all Syncing, indexing and optimization had to run again.
I think your workflow is impacting your battery.
I think your workflow is impacting your battery.