Wrong quality and codec

VDownloader is great most of the time, but once in a while it saves in the wrong quality. A video that would usually be saved in 480p and with an H264 - MPEG-4 AVC codec has just saved in 360p with a Google/On2's VP8 Video (VP80) codec. I don't know much about codecs and things, I just want VDownloader to save videos in their original quality again. Thanks.