Yes, you can. You have several options. You can:
- select a specific internal visualizer
- select a visualizer and display it randomly
- select a visualizer when loading a track and display it
- select video in a specific folder and display it
- select video in a specified folder when loading and display it randomly (I use this a lot)
- select video in a specified folder when loading a track and display it
- display artwork of the track
- do nothing
You actually have the ability to handle deck 1 differently than deck 2, although I don't know of a use case for that.