I seriously thought this had been SS'd already and hadn't checked the leaderboard, so I exited out of the results screen to see that I in fact was first to SS, hence the lack of results screen and lack of some details.
Osu! is a rhythm game based off of Osu! Tatakae! Ouendan! and the American release Elite Beat Agents. In these games you click circles to the rhythm of the song. Osu! also has different rankings you can shoot for, with SS being the best (Hit every note and have 100% accuracy). THere are also mods like Hard Rock, Hidden, Flashlight, and Double Time/Nightcore if you want to increase the difficulty even more.
There are 4,503 views in 935 videos for osu!. His channel published over 1 day worth of content for the game, roughly 21.26% of osu! content that JonathanScarlet has uploaded to YouTube.