Since there were some streaming issues here is a summary and some video clips of NKOTB's appearance at the Boston Strong concert:
Donnie gave a speech...
Video courtesy of Sameolsong90
Then the Dropkick Murphys came on stage and performed. The Dropkick Murphy's ended their set with "Shipping Up to Boston", then NKOTB joined them on stage and they transitioned into "Hangin' Tough", then NKOTB performed "The Right Stuff". Then they were joined by Bel Biv DeVoe. BBD performed "Poison" and NKOTB danced in the background. Then they performed "Please Don't Go Girl" and "I'll Be Loving You Forever" and "Step By Step". Donnie introduced Boyz II Men and both groups performed the song "One Sweet Day".
Here is the complete performance courtesy of berlinasxo:
NKOTB came back on stage for the encore with all the other performers and they all sang the Beatles "Come Together" followed by "Dirty Water" by The Standells (which is a song traditionally played at some sporting events in Boston, you can read about the history of it here).
Video courtesy of Bhthing Nkotb