In this ear training video, Geoff Peters talks about musical intervals and introduces the concepts of the tritone (also known as augmented 4th or diminished 5th) and the major third.
There is a short Quiz section where Geoff invites the viewer to identify some intervals, and then Geoff performs an improvised blues piece.
In this video, Geoff Peters plays various chords on the piano and invites the viewer to determine whether the chords are major, minor, or dominant seventh chords, as well as identify the key.