How do I enable hardware accelerated video in VLC with Intel HD 4000 GPU?

VA-API (Hardware Acceleration For Intel )

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for Intel GPUs (for Intel HD Graphics as well as G45 and later):

 sudo apt-get install i965-va-driver libva-intel-vaapi-driver vainfo

Configuration

VLC

Its in Tools > Preferences > Input & Codecs > Enable Use GPU Accelerated decoding

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How to correctly enable/test VA-API on Intel Sandy Bridge?

 vlc --ffmpeg-hw -v

Check the line

 [0x7fd018c02d38] avcodec decoder: Using VA API version 0.32 for hardware decoding.