I may be missing the point here, but...why are we going to these tab sites? If it's to examine, study, learn from the techniques of established performers, then I believe the "fair dealing" principal of copyright says that's OK. If it's to reproduce the performance in all its detail, then its a breach of copyright, and if we're so damned in love with the music tradition, why do we want to reproduce someone else's performance? I get heartily sick of putting the effort into arranging and rehearsing, only to be asked "didn't so & so record that?" Well maybe he did - and your point is...?
Sometimes I wonder if we are going down the path of every other field of instant expertise - get the magazine and become a (select topic)wizard. Go to a session and spot how many guitarists have learned from the same video. It's enough to make you take up the bouzouki. What about a bit of originality?
Chris N