Is it possible to edit default wallpapers?

[War Pig]

I wanted to add some basic text to one of the default video wallpapers. Is that possible?

[Mystix]

Most likely. I'd suggest to go to where Wallpaper Engine is installed on your computer, go into the "projects" and then the "defaultprojects" folder and you will see it contains the default ones. Then make a copy of the one you want to edit and paste it in a different location to then edit as you want.