I can't hear gameplay audio when I record with a microphone

[Sonic-Keyblade 007]

I'm currently using a Dell Precision m6500 laptop running on Windows 8.1 and whenever I record gameplay using Dxtory and a microphone for live commentary, I can barely hear the gameplay audio. I can hear my microphone just fine but no gameplay audio. I even tried following this video: https://www.youtube.com/watch?v=CJFwZkQbbAw but I still can't get it to work. Does anyone know what I'm doing wrong? Thank you for your time.

[RobiePAX]

My post from a different thread, but it likely applies to you too:

It's possible that you are misunderstanding how video players and audio tracks work. Video player can only play "1" audio track at the time, you can switch between them but can't play all at the same time.

You can extract all the audio tracks from the video by right-clicking on the Dxtory video - select Extract Audio Streams - and then combine all those streams in a video editor. Manual audio extraction is not required ONLY in Sony Vegas, in all other video editors such as Adobe Premiere you have to do it manually.