I am running iPhone iOS 4.2.1 (3GS) and my DVD to iPhone conversions have resulted in choppy video since November 2010. This happens during dark or underwater scenes (Piranha, Expendables, Salt...) and results in the audio continuing to play correctly but the video becoming choppy and pausing on a frame for a second or two then showing another frame and pausing. This happens consistently during darker scenes and immediately clears when the scene shifts to a brighter scene. This has been happening since last November and I have updated my DVDFab twice since it started. I have gone back and viewed movies that I converted before November and they play fine on iPhone. Also, all the videos (before and after) play fine on iTunes and Quicktime. I use the default conversion settings (only thing changed is audio to 300% and check forced subtitles only). I commute on the train every day and watching movies with choppy video is becoming frustrating, please help.