Yocraft: a free, online, multiplayer Minecraft server, which Tyler and a group of other people spent months building and hundreds of dollars on.
Part 3 of the Mario 64 co-op LP- Tyler and Super Jeenius struggle with the Cool, Cool Mountain slide for almost the entirety of the episode and have to deal with the penguin race, which is a two-fold moment.
After several attempts, Jake (Super Jeenius) finally successfully tricks the slide out where he jumps onto a later portion of the track and beats the penguin... only to be disqualified.
Then in the very next attempt (possibly only the next one shown), Tyler and Jake slide on the track fair and square, and Tyler manages to beat the penguin legitimately.
Part 6 of the co-op LP, Tyler manages to complete the owl mission where Mario has to drop into the cage in one try. It's already considered one of the harder missions in the original game, but to do it in one try even with the mod's wonky camera focus is pretty impressive.
Which was later matched by Jake doing a long-jump/wall-jump across the gorge in Cool, Cool Mountain in that same video.