Faster video playback without tiny voice

My university records the lectures and uploads it online. The online player allows the playback speed to be set at 2x yet the voice is still understandable. (panopto)

I tried downloading the video and playing it 2x speed using MPC-HC. The audio is also sped up as that it sounds tiny.

How does the online player keep the audio in sync but not distorted. How can I recreate this in a local video player?