Using native backends for reading video files

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Hello,

I am trying to extract frames from a video by only using codecs that are available on user's computer. The computer is a Windows OS. My understanding is that it is possible : http://docs.opencv.org/trunk/d0/da7/v...

But i am only able to read video from my webcam and not directly from a video file.

Am i missing something ?

Thanks in advance,