Fix windows video selection for extraction in the GUI by KonradDanielewski · Pull Request #2286 · DeepLabCut/DeepLabCut

@KonradDanielewski

`QtWidgets.QFileDialog.getOpenFileNames` outputs unix formated paths which on Windows leads to wrong reading and uninformative output "Video file corrupted" which isn't true. This fix normalizes the path according to `os`

n-poulsen

@n-poulsen