blank screen in Fusion

i've compiled some moving text on top of footage of presenter. now i need to turn the footage visibility off, so i'd get only the graphics to place on top of the actual footage to grade those tracks separately.
but when i turn off the MediaIn node, the whole screen goes gray

Well, yeah. MediaIn typically feeds the whole chain of effects.

There are color effects in Fusion, which you can add only to the Presenter clip.

Well, yeah. MediaIn typically feeds the whole chain of effects.

There are color effects in Fusion, which you can add only to the Presenter clip.

how then to add graphics to footage, but then turn the footage visibility off (to get the graphics only)?

Add the moving graphics in Fusion. Start with just the original clip.