Always remember one thing: the sound that you hear depends on the device you are getting the output through. As you say, you like the sound through your amp but not from the software, this is because you probably use the same settings on your pedalboard when you plug it into the interface as you do when you plug it into the amp. You need to check the output of the sound through the audio interface and/or what is received by the computer and make the settings accordingly. This can be done best if you switch off your amp and plug in headphones into the interface and then hear how the sound is and adjust the pedalboard controls accordingly. If you fail to get the best sounds from the available controls on the pedalboard, interface and the software, then try using the software called Amplitube. Also, learn how to use plugins in nuendo to make guitars sound better.
Let me tell you about the "bright sound" you hear in other youtube videos. Mostly, distortion guitar sound is not recorded by plugging in the guitar from the pedalboard to the interface, but using an instrument microphone and record the sound directly that comes out of the amp. That way, you can get the bright tone of your guitar recorded as you hear from the amp without using additional software. So, it will be best if you buy an instrument mic like the SHURE SM57.
Recording guitars is a lot different from recording digital instruments like the synth. How you record determines the quality of your sound. As you now see, plugging in your guitar into an interface is not always the best idea for recording distorted sounds. However, if you have to record it without using a mic, then you just have to adjust the pedalboard settings according to the interface output as you'd hear through the hedphones. In this method, you may have to use artificial effects and plugins to get that bright tone.
Hope it helps.
"Artificial" effects don't make you a fake musician
These effects/software are used only to make the recording sound as real as possible. You'd obviously be giving your real efforts to play the instrument in the first place. So, there's no chance you'd be a hypocrite by using plugins and effects. It's just that we humans are left with no other option to make the computer do what we want out of it. Relax! :-)