It's called I Wish I Knew How It Would Feel To Be Free. I've just dug out my 7" of Billy Taylor's original (instrumental) version and it credits him as the writer, though the words may be by someone else.
For the benefit of headrush, it is the same tune. The Film (insert year of choice here) theme is the Billy Taylor version mentioned by jenstar.
Probably the best known vocal version was by Nina Simone.
The thing that perturbs me about the ad ( and I know this isn't answering the question ) is that the bottles are already opened.What sort of sicko does that?
Someone who wants to put date rape drugs in ur bottles. It's not a very good safety advert is it?! I mean would you take an opened bottle of drink from a stranger and actually drink it!? Or look pleased about it?! Weirdos.