It's not accepted, because you can't extract a raw memory card file onto your PC to submit, without having a Sharkport or MAX Drive, which convert the raw file to .sps/.xps or .max format automatically!
The only way to submit a raw mem-card file is to physically deliver or post your card to the race steward, or another member close by to you that can make a submittable replay file for you.
If you're talking about video capturing the GT4 replay onto your PC and submitting that, then they're not considered valid since you can easily edit a video file. People have tried this in the passed, and been banned from GTPlanet as a result!