a drawing like an image to show over the video? It could a variety of things like set up a list of videos and have it select a random one if you wanted different loading screens that would be easy If you wanted the option of picking a random loading screen video to play from a list that would be easy to add in at this point.
As far as drawing an image that's really easy to implement as well but would it just be static? should it fade in and out? should it be an animated video like a video stack where your gif could be in video format and just stack it on top of the other video? doing something like stacking a video on top of another video would make it possible to have different loading bars while keeping one video in the background the same. there's literally tons of possibilities here lol
I'm actually getting kind of close to finishing the basic loading screen functionality already, though I haven't tested anything at all yet but It's pretty straightforward to implement.