Advice please: Copyright on a remix

[Patchen]

Hi all,

I recently remixed a well-known song and uploaded that to youtube (non-profit). I am aware that ideally I should clear all samples before doing this, but also that it is difficult for a less-well-known artist to get samples cleared, and it can be expensive. I am also aware that "dance remixes" tend to be tolerated by record labels since if it ever becomes popular they can claim back royalties.

I got an email from YouTube this morning saying:

Your video may include the following copyrighted content:

Musical Composition administered by:
Warner Chappell

[I acknowledge]
[I believe this copyright claim is not valid]

Is this an automatic response, or have the record label submitted this?
Should I acknowledge or not?

It's marked as "matched third party content", which is true for the acapella on the track but not for the production/music etc.

I don't want my video to be recognised as an upload of the original song, but I don't dispute that I do not own copyright on the actual music/lyrics. If Warner wanted it removed I would be happy to remove it as it is partially their content.

The video in question is here: http://www.youtube.com/watch?v=4-prMsPVwf4

Thanks