The container should be (Matroska). Do not accept .exe, .scr, or .zip files that claim to be the video. A legitimate Complete HDTV -x264- will almost exclusively use MKV due to its ability to hold multiple audio tracks and chapters.
Just remember: When you play the game of downloads, you either win (find a healthy, well-seeded complete pack) or you die (download a virus-ridden .exe file claiming to be Episode 9). Choose your torrents wisely. Game Of Thrones - Season 2 Complete HDTV -x264-