Hi, Quicktime does not want to start the .AVI files. Only .MP4 files works correctly. http://d.pr/i/IJAS The Perian support is no longer maintained and was last updated for OS X 10.8. MPlayerX does not work on OS X 10.9 (RIP more signal developer since early 2012). VLC is more than I but less well optimized as MPlayerX. Someone of you has the same problem as me on Quicktime?