The Pre shoots 640X480.
And We really need a test with a Class 4 and Class 6 card to know for sure. Video compression is half science and half art. But both halves drop low contrast details first.
If the phone can record great details, but the card is too slow, either the phone drops details to meet the recording speed of thecard, or the card drops details as it tries to keep up with the phone's data rate.
If a faster card makes no difference, then we know the phone can only write at 2MBps. In which case, we record at 720p and downsample to 480p for the best video quality. On the other hand, if the faster card looks better, then we know the phone can do better, but it's up to us to feed it properly with Class 4,6 or faster.