I read this thread a few days back and thought about it and came across it again today. I think everyone has made good points, but I still wonder how can you cover something like this. So below is an idea for a disclaimer I came up with.
"Lessons contain both advanced and student level playing. The advanced is presented so students can hear and see what the lesion is trying to teach. The student level is to show what they will need to complete, before they can play and barrow from the lesions."
To me wording kind of like what I presented above address the problem in a way that would cover the site, while respectfully presenting information to readers.