Can you tell what roll pattern is being used here? Hint: pay more attention to the pick hand fingering - TIMTMITM. Roll patterns are not tied to any specific string sets. They can be used on any strings or even a single string. The pattern is based on the order in which the pick hand fingers are used.
The chord changes for the A and B section of this tune are the same. That's why we only need these for measures to get us going on this tune. The form for Angelina Baker, like most other fiddle tunes, is AABB. So if we play this backup here 4 times, we've gone through the song once. Try to memorize the basic backup then play along with the melody in the key of D.
After getting the basics down try out some licks to diversify your backup skills.