I have Melodyne Editor. And there are many things about it that I don't know, or don't use in my daily work flow process. In all the videos from Celemony, everything that I have seen and duplicated have worked. It's just that I don't often use it to it's full potential in my workflow.
First, a correction. Essential may only be monophonic but that simply means it only works with a melody that has one note played at a time...such as a singer or a sax. You can still use the monophonic version to create a harmony line. You would need the full version of Melodyne Editor (ME) in order to work on polyphonic material such as piano or guitar chords. If you can move the blobs, you can create a harmony with it. You might need to work in a separate track, but it can be done.
Second, there are things in ME that I know are there, and they work, but in actuality, I have never used them in the way they are shown in some of the tutorial video's like this. I keep saying that I'm gonna try that next time I need to do that BUT....I tend to forget when I am working with it and resort to what I have done before that works.
This song:
http://soundclick.com/share.cfm?id=12024980 is a good example for me to use. The singer recorded this at her father's studio and sent it to me. Work schedules and life in general prevented her from being able to record any harmony tracks. Yet, in the Pre chorus and the chorus you can hear harmony parts.
How I did it:
In Sonar, I inserted a new audio track and cloned./copied the lead vocal track to it. I inserted ME and simply used it to load the PC & Ch parts and then dragged the vocal blobs where I needed them, manually, one by one for the parts I needed. I would move the blobs and then play it back with just an acoustic guitar track so I could hear if the note I dragged to worked or not. It really doesn't take very long to complete a PC or a CH or even a verse working like this. It's probably faster than setting up a mic and doing a bunch of takes and then having to pitch correct them anyway. I set up volume envelopes to keep the levels where I needed them and bring parts in and out.
The biggest problem with this method is the artifacts it leaves behind.
This is evident even in the vocal sample on the youtube video you linked to. At the very beginning, you can hear the artifacts, the robotic sound is hard to disguise. And yeah, my harmony parts sound similar when you solo them. In order to work around that, I keep the BGVH low in the mix. Since I normally keep my BGV and BGVH low anyway, its not a big issue.
The further you move the note from where it started, the more prominent the artifacts and format issues will become. Melodyne does allow you to adjust the formants of the notes.... the problem, at least for me, is that I have not yet mastered the editing of the formants to make that new pitch sound like a normal singer singing that note naturally.
Hope this helps you.