If my understanding is correct, and this is a big "if", the .ifo is only
part of what comprises the actual dvd. The fact that you said that it's only 128kb in size also makes me think it's only part of the dvd.
EDIT: Rereading gunug's post, I think this is what he was saying.
From Dolphin's link above:
QUOTE
...An info file associated with a .VRO video file. The .VRO file contains the video stream and the .IFO file contains various scene and timing information. This is different from a .VOB file where that information is included in the file. Several manufacturers use .VRO/.IFO files. If present, the file VIDEO_TS.IFO consists of control and playback information for the entire DVD. VIDEO_TS.IFO is known as VMGI (The Video Manager Information file). This file is required to be present on a DVD-compliant disc. .....