The Easter Rising (also known as the Easter Uprising or Easter Rebellion) happened in 1916, so they were commemorating the first centenary when we were there.
Here are some articles to read about the issue:
Easter Rising (History)
Another video about the history of Ireland >>>>
and this one about the Easter Rising >>>
By the way, have you seen the film Michael Collins? Here's the film trailer. Michael Collins speech
And do you know what the Good Friday agreement is?