Export animations to videos

I totally understand that three.js is a client side, but want to confirm if it reachable to have an animation into a video or lets say images using server side?

You can use three.js to render applications on node.js. There are several discussion about this topic like this one:

three.js can’t directly render a video for you but you can do it by yourself by using a library like FFmpeg. That is how the editor does it: