This version does not use the original song by Aria Rose and is instead sung by Yuri Tsukito, while the instrumental is by Sully Orchestration.
There are a few new scenes that aren't in the original Megalomaniac that have been added to this version.
Half of the animation was animated by Jakei95 while the other half was animated by Superyoumna. This shows the reason for the art style that changes in half of the video.
Camila wanted to either re-animate Megalomaniac or release the next episode but since she got terribly sick, she lost way too much time, and since the fans had an incredibly high demand for My Promise, she had no time to reanimate it.