I see how I can restrict my requests to certain types of media, by putting that into the details/prompts field.

But I can't see how I can restrict my offers to certain types of media.

I can only offer one type of fanwork (and it's not fic), so how are you going to match me to anyone if they don't specify they'd like to receive this? I am uncomfortable working with fic prompts because someone who expects a fic and gets a gifset will be unhappy.

And then let's say I absolutely want a fanvid, how are you going to find someone who is able to offer a vid?