Freelance Astronaut Pipes! is somewhat famous for his creative use of profanity when his smack talking distracts him to the point of playing himself into a corner during multi-player sessions with the other Astronauts.
slowbeef occasionally lapses into this, during both Let's Play and Retsupurae videos. In particular, his first encounter with a Kinetic Orb Cannon in Metroid Prime 2: Echoes completely destroyed his ability to speak coherently.
While strictly not Let's Plays, BrainScratch Comms Commentary of Sonic Genesis has several great examples including, but not limited to, both the beginning:
Ryan: Why? Why!? WHY!? WHY!!!!????
Ryan: "How're we gonna keep this anger up for the whole commentary?"
Johnny: "I will find every neurotic excuse I can"
And the entire final part, which includes an unending loop of anger, and one exquisitly hilarious glitch.