The sudden virality of the first "Let's Kill Da Ho" moment after being shared by Anime Girls Speaking English on Twitter had brought about a spike of new viewers to both Pikamee and Tomoshika (have the second moment too).
Newfanart was made, Tomoshika retweeted and then individually tweeted about it, Pikamee changed the source stream's name to draw more folks to it, and to cap it off, they did this voice-over on Tomoshika's channel.
The music in question is derived from the end of GYARI's song "Zettai ni Chocomint wo Taberu Aoi-chan," being exactly what it sounds like, a knock-off Roundabout.