Adding an animated green screen background is simple, just go to the "green screen" set up in your event on the SNAPPIC online portal and instead of adding an image, you can now add a video that loops in the background, it will use the same amount of frames as your GIF or Burst Requires.
You can upload multiple videos for your guests to choose from.
Most of the videos are recorded in 24 or 30 fps (frames per second)
GIF can have up to 6 frames and Burst can have up to 16 frames, this means that it will only use the first frames to create the animation.
The video must be:
Less than 10 MB,
720p = 1280 x 720 (or the same aspect ratio as the template you have uploaded)
A couple of seconds long
It must also be a loopable video, ideally but not required
Videezy and Pixabay are good resources for free stock video footage.
Alternatively, you can also create videos with images to create some custom animations. The Adapter is a great tool and it is free!