Sinéad left out some of the song.
Usually the third verse is
"The people were saying no two were e´er wed,
But one has a sorrow that never was said,
And I smiled as she passed with her goods and her gear,
And that was the last that I saw of my dear."
and the last verse should start:
"last night she came to me, my dead love came in"
This is where the young man denies that he murdered his young love.
In the last verse we hear the line, I dreamed last night my young love came in. The original line is, I dreamed last night that my dead love came in (implying she haunts him for what he done).
The song has been used in several movies including Brave Heart.