这是VV3的readme中的一段说得很明白：
File size limitations (FAT32 and NTFS disk drives)
AVI files larger than 2GB are supported by the OpenDML file standard, (also called "ODML" or "AVI version 2.0"). This means Vegas is limited only by your operating system and/or file system (how your drives are formatted).
· Drives formatted as FAT32 under Windows 98SE or Me allow files of up to 4GB.
· Drives formatted as NTFS under Windows 2000 and XP do not have a 4GB limit.
By default, Vegas creates OpenDML-compatible files. This allows you to render large AVI file sizes. Some other applications may not be ODML compatible and may not be able to use these files. To change the default behavior, go to the File menu, choose Render As and click the Custom button. Then, on the Video tab, clear the Create an OpenDML (AVI version 2.0) compatible file check box.