Dxtory Codec and some others are being installed automatically when you install the problem, you somehow managed to corrupt the codec.
1. Firstly go to Control Panel - Programs and Files - in the search bar in right-top screen type "codec" - and remove all codecs which you find unless you know you will definitely use them such as Lagarith Codec. After uninstallation restart PC (important).
2. Next install K-Lite Codec Pack (download link: http://goo.gl/Dk5OmY ). During installation installer might detect corrupted codecs on your PC, allow it to remove or fix them if it detects them. Don't worry, K-Lite integrates itself into Windows Media Player so you don't have to use a different player.
3. This is optional step, but it's best to do it. After K-Lite installation you should open the newly installed "Codec Tweak Tool". There select "Fixes" - Tick everything and Apply. Next click "Reset", tick everything and Apply.
4. Restart PC and you are done. You may have to record fresh footage to start seeing the video.
This should solve your issue. If you'll have any other issues with Dxtory or Gaming video encoding you can ask away at Encoding Talk Forum for a quick reply: http://EncodingTalk.com