Because most people don't ask for Final Fantasy megamedleys, and most artists fulfill requests with the intent to submit to OCR later on.
They are, but if you included every single track in your request, it would be much too long and big to be accepted. This is why Bladiator can't submit "Golden Ivories of Gaia," an incredible FF7 medley from VotL, and Jeremy Robson had to split his "Philharmonic Suite" into several pieces.
Um, you're the one who said your request was for a video project you were working on.
This is a lot more reasonable. See my above recommendations by Bladiator and Jeremy Robson.
Not really. Magma appeared to be asking for a 13-track medley, which would a huge undertaking much beyond the scope of most simple requests on this forum. Furthermore, it would inevitably be too large to submit to OCR, making it a custom work. I don't feel it's unreasonable or inappropriate to ask for compensation for what is essentially a commission in this situation. It would certainly improve his chances over asking people to spend countless hours out of the goodness of their hearts. If you happen to find someone who wants to do exactly that though, well then more power to you.