Here's the codecs needed for playback viewing on your PC

For DVR with version 3.0.0.332 and more :
Codec FFDShow (.EXE)
(Archive version, Only if you cannot download the .EXE (ZIP))

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For DVR with version 3.0.0.325 and less (Including version 2) :
Codec Xvid (.EXE)
(Archive version, Only if you cannot download the .EXE (ZIP))