Ahh, now it's starting to become clear. On the Recording Controls -> Properties and I check on "Recording," I notice that "Stereo Mix" should be there, correct? Now, I only have CD Volume, Front Mic, Mic Volume, and Line Volume, but unfortunately, I do not have "Stereo Mix."

Now I did update my Realtek two days ago I believe and on the Realtek Manager, I received the following options on "Mixer -> Playback: Rear, Subwoofer, Center, and PC Beep." They were never there before. So that's new, but still no sign of Stereo Mix. So if it's not located on my computer, then there's no way to record Youtube videos or computer noises, right? Becuase I have no idea what the repairman has done to the sound card.
But I do have the Enable Playback Multi Streaming, and all it does is silent everything. I also see that someone else is experiencing the same problem as I am and was told that my Realtek AC97 might not support Stereo Mix, so there isn't any other way?
Mike