Can't use webcam in Openvino python Demos

[wupeng8888]

[ WARN:0] global ../opencv/modules/videoio/src/cap_gstreamer.cpp (713) open OpenCV | GStreamer warning: Error opening bin: no element "cam"
[ WARN:0] global ../opencv/modules/videoio/src/cap_gstreamer.cpp (480) isPipelinePlaying OpenCV | GStreamer warning: GStreamer: pipeline have not been created
libva info: VA-API version 1.6.0
libva info: va_getDriverName() returns 0
libva info: User requested driver 'iHD'
libva info: Trying to open /opt/intel/mediasdk/lib64/iHD_drv_video.so
libva info: Found init function __vaDriverInit_1_6
libva info: va_openDriver() returns 0
MFX: Unsupported extension: cam
[ERROR:0] global ../opencv/modules/videoio/src/cap.cpp (142) open VIDEOIO(CV_IMAGES): raised OpenCV exception:

OpenCV(4.3.0-openvino) ../opencv/modules/videoio/src/cap_images.cpp:253: error: (-5:Bad argument) CAP_IMAGES: can't find starting number (in the name of file): cam in function 'icvExtractPattern'

[ ERROR ] 2020-05-13 18:09:39,469 Cannot open input stream: cam
[ INFO ] 2020-05-13 18:09:39,469 Input stream info: 0 x 0 @ 0.00 FPS

I run the demo of face_recognition_demo.py , but these is a error . I use Intel NUC, Intel(R) Core(TM) i5-8259U CPU @ 2.30GHz

[Maksim_S_Intel]

This is documentation issue, you should use numbers (e.g. '0') as script '-i' parameter instead of 'cam'. I've filed an issue: https://github.com/opencv/open_model_zoo/issues/1102