Build web-based video player with audio switching

We need to build a simple web-based video player. The goal is to show examples of how our software can improve the audio in their video clip. Here are the requirements:

– The video player will allow the user to choose from six pre-loaded video clips.
– For each video clip, there will be a “before” version and and “after” version.
– The user can toggle between the “before” and “after” audio during playback.

This player will be embedded in our WP-based website.

We have a v1.0 of the video player here (scroll down to “remove the noise, amaze your audience”):

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But the current player has a glitch when the user toggles on/off. We want the playback to be seamless when the user toggles on/off.