If you have a sony camcorder, when you transfer a video to your PC, you will probably see three files with the file extension Moff, MODD, and M2ts. The last file is the actual video files while the ones with the file extension Moff and Modd are metadata files which keeps data such as date, time, etc. It is important that you keep these files in case you're converting the M2ts files just to be safe. Modd and Moff files are associated with the picture motion browser application that comes with some Sony Handycams.

There are a lot of video converters that can convert M2Ts Files to MPEG files but this tutorial on this forum: www.digitalbhoomi.in/forums/showthread.php?t=9586 gives a detailed walkthrough on how to convert most of the popular video formats to iPod/iPhone video compatible formats.