This is a short reel, with 16 bars. It's in the key of E Minor, with two sharps in the key signature, which means it's in the E Dorian mode.
Tony sometimes refers to this as the "Irish Minor", and many Irish minor tunes use a Dorian mode.
Listen to the lesson (TheAshPlant.mp3, 13 minutes 57 seconds. 4.79 MB)