The Drop Kick Murphys - Shipping up to Boston. The video has nothing to do with the lyrics, but that's not unusual with professional videos these days.
Flogging Molly - Seven Deadly Sins
The Tossers - Good Morning Da. This is a very fun video and actually follows the story of the song.
Mumford and Sons - Little Lion Man. Yes, I count this as Celtic rock. They are part of a movement in the UK to bring folk music back into the mainstream. Pretty much exactly what the Celtic rock groups here are doing except for us it's imported folk music.
Unfortunately, I couldn't find any videos of my favorite Celtic rock group - an Australian group named Brother. They broke up before the advent of YouTube and cell phones with video, so nothing has been posted on them.
Other groups you might look up - Seven Nations, The Blarney Brothers, Six Mile Bridge, Blackmore's Night.
Who's your favorite Celtic rock band?