Hey,
I'm the co-founder of Weezic,
Thank you very much for your feedback.
The definition of the product we are trying to explain on our landing page is actually: for each work = scores + accompaniments + your interpretations.
That means on Weezic, in addition to the score you get all customizable mp3 files to play your part of music, whatever your instrument is (just like you would do with MIDI generated formats but with a much better quality).
In addition to the video we have a demo on the landing page: you get access to it by clicking on the 3 right menu items (I'm not sure you've seen it, it's not particularly highlighted, which could be a mistake in our design).
Convenience is a good word for our starting value offer, but "Enhanced experience", although less precise, would actually be a more exact definition of what we are offering: "You're a musician and you want to play a work? You'll find it easily on Weezic with all the ressources you need to enjoy playing it: Scores, Customizable accompaniment files in high mp3 quality and other musicians to share it with".
I hope this answers your questions about the offer.
Regarding the business model, people will have to pay to access our content (scores + accompaniments, etc.) but the user-generated part will be free of course.
If you're interested in the project you can contact me at: nicolas@weezic.com
If you're in Paris, why not have a beer and discuss it in more details. Thanks again for your feedback!
ps:
I hope my reply is in line with this forum's rules as I am new to this forum and new to the web dev community.
Please also forgive any mistake in my english as I am French.