How to create a video background
An animated video background can add a nice visual effect to your page.
Everything starts with a nice video (.mp4) that you can use as an animated background. They're quite easy to Google and sometimes cost a bit of money. Or you can create one yourself in After Effects. Make sure it loops nicely, is not too big and has decent quality.
Once you have one add the Video component from the Insert menu. Select Upload and add your .mp4 file (50mb max). Then set play to on and mute the sound (so that autoplay works in most browsers). Finally you can lock the layer so that you can easily draw other contents on top.