I don't think you will the this.
First this is not the intention of AS, it is build to be a simple downloader for everyone, without the need to deal with cmd and so on. And maybe you know how to find the links needed, but when they add this there will be plenty posts in this forum how it works because I think many users will not understand this.
Second the other providers can use a different implemention of WV, see the SD issue with Amz: Amz changed something, but NF was not affected. Only Amz was limited to SD and D+ is still 720p.
So even if they add it, you could get plenty DRM licence errors if the provider uses a way AS don't work with.
At the end it might be better as is: Only add a new provider when they managed out how it works so everyone can use it or if it would be possible (this is up to the devs) then add a big text into the url input window that this is only for expierenced users or that there can be errors. But even then I can already see many posts that people are not able to use it or "how do I get the links".