http://www.videolan.org/ is one of those programs that makes everything better. Give it any kind of file at all--avi, mp4, ogg, mp3, mov, literally anything at all--and VLC will play the hell out of it. Also the latest release of the mac version integrates beautifully with the OS, making it far sexier than the bundled Quicktime or any other option. If you watch any video at all on your mac, you need to get VLC. Download it "here":http://www.videolan.org/vlc/. Previous _Killer Apps for Mac_: "Adium":http://duenos.net/article/129/killer-apps-for-mac-adium, "Sidenote":http://duenos.net/article/111/killer-apps-for-mac-sidenote, "Darwiin Remote":http://duenos.net/article/193/KillerAppsforMacDarwiinRemote, "Mac Pilot":http://duenos.net/article/174/KillerAppsforMacMacPilot, "Disk Inventory X":http://duenos.net/article/163/KillerAppsforMacDiskInventoryX, "Tangerine":http://duenos.net/article/150/KillerAppsforMacTangerine, "SizzlingKeys":http://duenos.net/article/119/killer-apps-for-mac-sizzlingkeys, and "Vienna Reader":http://duenos.net/article/204/KillerAppsforMacViennaReader.