Ask HN: How is this online code screencast tool called?

A while ago here on HN someone shared a screencast of someone coding. This was an interactive browser-environment where you can see the code being typed, and copy-paste it.

There was someone presenting (webcam) in the bottom-right corner.

There was also a timeline so you could seek through the screencast. When seeking, the code displayed was synced to the video.

Simply put it was a combination of YouTube + VS Code.