Even disregarding which codec Youtube uses, there's also the question of what codec was uploaded(unless it's an official upload), which in many cases was probably a lossy codec in the first place. So often you're listening to some lossy codec, reencoded to another lossy codec.
CDBaby only provides one format, which is mp3. They'll accept uploads in any of four formats, of which one is also mp3.
So you'd need to answer two questions:
1. Is the file that CDBaby distributes to YouTube the same file they distribute to everyone else, or is it the same file they receive from the artist? (Note: if the answer is #1, that is likely to save CDBaby a bundle on storage!)
2. What did the artist upload to CDBaby?
And then you'd also need to answer analogous questions for the other major providers of official music on YouTube; there are tons and tons of them. CDBaby appears to be unusual in that, in addition to providing your music officially to YouTube, it will also sell it to consumers. Most of these services don't appear to offer anything but official distribution to major websites.
