SDL_Overlay as surface changes

Just wanted to get some feedback on using SDL_Overlay as a surface.
The basic reason for it is to be able to blit regular RGB surfaces to YUV. It will look like OSP above the playing movie or video stream.
I have this functionality working perfectly in DirectFB with all HW acceleration it may offer, so it feet my needs.
And I want to be able to use SDL for this kind of purposes, so I decided to hear some feedback from you before doing that.
Basically it would be only one additional public function which will return SDL_Surface out of SDL_Overlay. And some hooks in blit funcs to do the job.

Let me know if anybody is interested or have any comments to share.