There's this video, "A" which worked on my phone the first time I transferred it over from my PC to the ext. SD. However, my external SD got corrupted when Kies froze in the middle of a transfer of another set of videos and after doing a reset of my phone (it froze too), it prompted me to format my ext. SD card since it got corrupted. Well, after doing that and transferring video A again, it can no longer be played. I then downloaded Rock Player but the app couldn't play the file either. I then connected my phone to the PC and manually formatted the ext. SD card from there and tried transferring video A again. It still can't be played.... =/ Any idea how to fix this or why it happened?