From the wiki entry about Google Videos: (https://en.wikipedia.org/wiki/Google_Video)
“GVI format and conversion
Google Video Files (.gvi) are Audio Video Interleave (.avi) files with an extra list with the FourCC “goog” immediately following the header. The video is encoded in DivX4 alongside an MP3 audio stream. DivX video players and various portable video players such as the Archos AV500 can render Google Video Files without format conversion after changing the extension from .gvi to .avi. Among other software VirtualDub is able to read .gvi files and allows to convert them into different formats of choice.
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AVI and MP4
Besides Flash Video and GVI, Google provides its content through Audio Video Interleave (.avi) and MPEG4 (.mp4) files. Not all formats are available through the website’s interface, however, depending on the user’s operating system.”
Transcode them before bringing them into Vegas, I say. If you can get an MP4 of the file (which not all will allow anymore), that’d be my first choice.
-Mark