two ideas.

first,
the last type of input, like image, or videos, should be the new default.
when you are entering a number of inputs of the same type, this would be faster.

second, and even better,

drag images / folders / videos
onto the input list.

I often have opening slide folder, closing credits folder, and a number of caption slides.
they are always organized together by project.

if I could select all of them, and drag them onto vmix
it would be one action, instead of twenty clicks.