I've just taken another look at the video. Its full name is "In Memory of Broken Heartstrings", and in the description, he says the following: Broken Heartstrings? Yep, Heartstrings suck, Lyra for life.



Heartstrings was the name that the character was given originally in Hasbro's My Little Pony toy line. However, bronies had already been using the name Lyra for the background pony in the TV show, and thought it was the more aesthetically pleasing, so as a compromise, they decided that Heartstrings was her last name, making her full name "Lyra Heartstrings". Eventually, Hasbro caught on and this design (turquoise, blue-and-white mane, harp cutie mark) has been called "Lyra Heartstrings" ever since.



Judging by what the composer put in his description, he prefers "Lyra" to "Heartstrings"; thus "Broken" Heartstrings, portraying his distaste for that name. I reckon that "in memory" is more of a reference to the song's contemplative and mournful nature.



The song can be found by typing "In Memory of Heartstrings" into YouTube. Incidentally, if you're interested in the Lyra/Heartstrings thing, you might like to check out "Always be Lyra", also on YouTube. It's hyper awesome.