This is a ‘very short’ (just a few minute) instructional video by Bill Bay. It teaches improvising development based on scales & arpeggios. It’s relative to all instruments and simply demonstrated on the guitar. There are many variations and ways to do the scale on the fiddle as well, especially using higher positions. The exercise is deceptively simple, so don’t miss the potential as a development tool.
Another great quote for it’s simplicity and importance. “Scales contain the notes of a key, arpeggios contain the notes of a chord. When improvising, match the scale to the key you are in, and the arpeggio to the chord you are playing over.” (Basic definition of improvising)