Googling "DV Type 1" gives this from Wiki
There are two types of DV-AVI files:
* Type 1: The multiplexed Audio-Video is kept in its original multiplexing and saved together into the Video section of the AVI file
o Does not waste much space (audio is saved uncompressed, but even uncompressed audio is tiny compared to the video part of DV), but Windows applications based on the VfW API do not support it.
* Type 2: Like type 1, but audio is also saved as an additional audio stream into the file.
o Supported by VfW applications, at the price of little increased file size.