Chess noises in lesson videos

If you navigate in a video with the arrow keys to go back a few seconds, a sound is also heard as if a piece was moved. I might be not only moving the video playback pointer but also the challenge board?

How are you getting the challenge board and video to show at the same time?

It's not showing at the same time, it just sounds like pieces are moving when I press arrow keys to navigate in the video

Can you point me to a specific lesson this is happening in? I tried a couple different ones and didn't get anything. 

Might be browser related so if you could let me know what browser you are on that would be great too. 

You're right, it's not like this by default, but I've been able to replicate it. If you go to the exercises, and make a move or a series of moves, then click on video, the board seems to be retained in the background and you can navigate the video as well as the moves with the arrow keys

https://www.dropbox.com/s/whgbd1ll0a1d5sz/2019-05-29%2015-53-36.mkv?dl=0

Excellent! Thank you! 

It appears this also happens when you complete a lesson and its challenges and click the orange button to the next video, then in the next one, you have the piece moving noises. That's probably how I go it the first time.