Right on, glad you're enjoying the lesson.
As for the bass, it is primarily playing what is known as a "walking bass line", which doesn't just stay on the root note of each chord, but moves through a series of notes to give the feeling of movement.
For example, under one meausre of the A chord, the bass will play on the beat with quarter notes, and play the notes: A, C#, E, and F#. Simply transpose this pattern down one string set and you'll find the notes to play under the E chord (E, F#, A, and B).
That should get you in the ballpark for a big chunk of the song. There are a few spots where the acoustic guitar plays a walk up or walk down, and the bass would simply play the same as the guitar in those spots.
Hope this gives you something to go on!