im saying it more detailed:you need to set up "OBS STUDIO" which the official site can be found here.
set it up and then add a game/app capture into your scene and choose veadotube when its open.
use chroma key in the filter of the capture and let veadotube open in the background.
sit back and use it because you can use it now!
(i would recommend experimenting with obs itself and its plugins which can be found here.)
have fun with it!