The Insanest thing you've ever seen.

[Scars Unseen]

Hmmm... I'm going to have to go with either

a) a stray fireworks rocket flying from a boat in the middle of a lake into the open window of an SUV filled with more fireworks, causing an explosion

or

b) Hello Kitty at Universal Studios Osaka singing an upbeat rendition of the Marilyn Manson version of "Beautiful People."


EDIT: Oh... in a game...

The glitch scene in MGS2 maybe?

 

[Rattja]

Basically, what's the most insane thing in any game of any sort? For me, I have to say watching two thousand people try to command a single character in Pokemon Red [http://www.twitch.tv/twitchplayspokemon] to be the literally most insane thing I have ever seen. Ever.

A little late to the party, but I have to agree with you there. Watching it now, and they have gotten further than I thought.
4 days, 4 gyms, not bad all things considered.
I've seen a lot of strange things, but this is by far the most insane of them all, wonder if they will ever make it to the end.

 

[Blitsie]

The entire game know as Asura's Wrath. Everything from the first to last missions is filled with insane, over the top action. You have space squids, giant elephants, rhinos, gorillas, turtles, and a cobra-turtle hybrid. One the other side you have Gods with nearly unlimited power. It's all just do over the top.

And to think a fight where a godlike being basically grows twice the size of Earth just so he can poke you to death is one of the game's tamer sections, haha. The ending DLC especially took everything and turned it up to 11.

Asura's Wrath was really the Gurren Lagann of games, now that I think of it. Such an underrated game too though, as lacking as it was in the gameplay department, the story and over the top nature made it really worth experiencing.

 

[Story]

I totally agree with you OP as well. That is really, really crazy and I couldn't stop laughing through the whole thing.
I was late to the party so I started watching with 50,000+ people playing but I did manage to catch up thanks to this fastforward video:

Before that the second most insane I've seen as far as video games go was World of Warcraft's Corrupted Blood Incident. Anyone remember that? I only saw a short video of it and it was nuts! I wish I could have been there.
http://en.wikipedia.org/wiki/Corrupted_Blood_incident