The first few notes already places you in the calm grass plains in the sun. I can imagine so much of the breezes in the wind that ruffles the grass. Despite so much breeze, everything still melts away. It's like Ed Harris' rendition on the guitar. He plays a much calmer one overall and doesn't have that extra life in the second part but the atmosphere he creates is so soothing.
Here's a short rendition of mine here in my house in Mexico City.
I only go through it once but I keep thinking of the spinning waltz couples in slow motion. Right now I always like to play it like there's a particular spin where when you're dancing in a couple's embrace, there is nothing else but you and your partner lifted into the serene clouds. Towards each end of the first and second part of Si Bheag, the tune gently puts you back down to earth. Do you hear those steps gently placing you back down?
Pete Huttlinger's video here has more of a nostalgic feel. Thinking of times past. This music goes through an old house and looks and lives all of the photos over the fireplace and all the memories of the times when children ran through the house. This rendition is slow enough to incorporate all of the harder struggles that happened... that somehow this tempo allows for a fuller palate of emotions.
And lastly with the TinWhistler brothers, a fantastic duo I found a few months ago, they combine their low whistle and guitar in a rendition that builds up the energy of the tune very gradually. It has the same feeling of being in a room with only yourself. The energy is calm and then after some time more and more family and friends join you and before you know it, there's food being set on the table and all of the plates and chairs lined up.