The Parting Glass

 This lovely song is from the ending of the film Waking Ned Devine, about a man who drops dead when he finds he wins the lottery, and since he has no heirs, the town conspires to pretend he is still alive so they can all share in the winnings.

I always assumed it was a traditional song, but apparently yes and no: according to the first video commentary:

Fill to me the Parting Glass was composed by Shaun Davey in 1998 for the closing sequence of the film Waking Ned; the words are traditional set to his new, original melody.

but that melody and the lyrics have a long history according to Wikipedia, which has a long essay on the song's history: apparently it was originally Scottish, and has many variations.

the melody of the modern version is similar to Old Cootehilltown: a song about leaving to work in America.

and the older melody was used in one of Bob Dylan's songs, Restless farewell, and one can see that although these are all different melodies, they have similarities to each other: something one sees in folk songs, which are often handed down by being sung, and those who write them down polish the words and melody.

One other note of trivia: No, the film was not filmed in Ireland as most people think. It was filmed on the Isle of Man, a small island between England and Ireland. The local government (that is semi independent) has tried to establish itself as a center for the film industry over the last 30 years. LINK but is best known for being the home of the tailess Manx cat.