The Video capture program bundled with SONY Vegas and later Magix Vegas has an interesting development history. There was the time before when SONY owned it, and the time after when Magix owned it. And inbetween it seemed to fall in quality and was revitalized or fixed after the acquistion.
The first of the great reawakening seems to have been during the Vegas 14 update releases, as a patch specifically mentions Blackmagic Decklink functionality had been repaired.
That meant Vegas 15 was the first to have it fixed "out of the box".
The readmes and release notes are well worth the time to read.
For Vegas 15 the readme is located in the file system after install:
C:\Program Files\VEGAS\Movie Studio 15.0\readme\Videocapture_readme.htm
It seems to be treated by this document as if its an entirely separated program, bundled with the larger suite of Vegas tools.
Thank you for purchasing Sony Creative Software Inc. Video Capture 6.0 software.
The next section contains a lot of tips and insider information regarding the program including advice on how to deal with certain situations.
2.0 Known Issues
Capturing to the same hard drive where your operating system is installed can result in dropped frames. If you have more than one drive, you can specify the target drive on the Disk Management tab of the Preferences dialog.
The next section covers DV specific information.
OHCI-compliant IEEE-1394 DV capture cards are required for DV device control.
Even if device control does not work, you may still be able to capture video by manually controlling your video device (e.g. pressing play on your camcorder's remote and then clicking the Capture button in Video Capture). If you are having capture problems, try clearing the Enable DV device control check box in the Preferences dialog.
If your DV camera is connected to another IEEE-1394 device ("daisy-chained"), the bandwidth of the IEEE-1394 channel may not be sufficient for print-to-tape operations. Connect each device to its own IEEE-1394 port before using print-to-tape.
For more detailed OHCI hardware, drivers, and DV information, visit the Sony Pictures Digital DV support page.
When using a digital-to-analog transcoder without a LANC adapter connected, clear the Enable DV device control check box on the General Preferences tab.
More information on genetic capture cards, and tv tuners
If you experience degraded system performance, clear the Enable still image capture check box on the Capture tab of the Preferences dialog.
If you experience problems using a TV tuner card or displaying closed captioning, clear the Enable still image capture check box on the Capture tab of the Preferences dialog.
If you're unable to preview an MJPEG-encoded file to an MJPEG external monitor, select the Close current device when in file playback mode check box on the General tab of the Preferences dialog.
Of (Major) interest is the same Vidcap program is installed with "Vegas" or "Vegas Movie Studio".
Movie Studio is a slimmer collection of tools and years later its much easier to find Movie Studio than the Pro or Edit editions of Vegas. It also cost significantly less than the Pro or Edit versions if you don't need any of those other tools.
Video Capture is automatically installed with Vegas and Vegas Movie Studio software.
Vegas 16 saw little change to this same readme in;
C:\Program Files\VEGAS\Movie Studio 16.0\readme\Videocapture_readme.htm
bit added a new one from the new owners "Magix";
C:\Program Files\VEGAS\Movie Studio 16.0\readme\Vegas_Movie_Studio_readme.htm
but seems to not contain any more useful information for the Vidcap program.