[vid2jpgv] Cygwin Missing & No error handling

[Traace]

1. Convert a mp4 h264 30fps video to jpgv via vid2jpgv
2. After temp extraction, jpgv compains that cygwin.exe is missing.
3. Get Video converted successfully message.
4. There is no output file.

Is cygwin needed for this?

The Script vid2jpgv.bat should be reworked, it contains no check about if the convert was successful for real or not. It just uses a predefined text string.