The girl at the beginning is Boxxy, a girl who posted some hyper videos on youtube, allegedly was a 4channer, and then disappeared. The people of 4chan fell in love/hate with her, some trying to find out who she is and where she went, others trying to spread false information to foul up the first group. Basically, how the collective internet male reacts to a cute girl: insane convulsions.
Then there’s “c-c-c-ombo breaker,” which is something done on forums (started on 4chan, of course) where one poster disrupts an attempt to have a series of sequential posts. Ever see one person post the first line of a song, then another posts the next line, and so on? Someone can disrupt that by posting “c-c-c-combo breaker!” It’s a fighting game term for when someone manages to “break out” of a string of linked attacks (combo) against him.
Then there’s Angry German Kid. He’s an Angry German Kid. That’s all you need to know.
After AYB is “Badger, badger, badger”, an early flash video meme by someone named Weebl. The same guy has a video called Owls, which I kinda love.
Don’t recognize the next one.
“Boom! Headshot!” is something people yell now in online/multiplayer shooters when they manage to shoot an opponent in the head (usually a 1-shoot kill). The term kinda came from that video, of a guy being way too into it.
Some J-Pop/anime thing I dont care about.
I dont recognize the anime bit right before bush shoe-thrower.
“It’s over 9,000!” A clip from Dragon Ball Z that’s kinda funny. Search it on youtube.
The girl who stares into the camera is a YT user called MRirian. Japanese-obsessed weirdos are in love with her because her eyes are humongous, like an anime character. Japanese weirdos love her even more. She’s tried to cater to this audience by learning a little japanese.
Those blue pokemons are called Mudkips. There’s a meme of “So I heard you like mudkips?” Basically, the joke is that someone would like pokemon so much they’d bring it up to a stranger.
Then it’s Lonelygirl15, a phenomenon a few years ago where this “girl” posted a bunch of videos, at least 2 or 3 per week, that after a while started to develop a plot. It got insanely popular, with people trying to find out if they were really video blogs or a produced stunt. When it hit the apex of popularity, it was revealed to be a fictional production. This became apparent about the time a secret cult that wanted to kill her neighbor/boyfriend came into the picture. They tried to capitalize on this by having sponsored product placement of some kind of sour gum. Then they really shot themselves in the foot and killed off the main character, probably because the girl (Jessica Rose, an actress) got the idea that she was going to be famous so she went off to hollywood land where she appeared on one season of an ABC Family teen drama and then disappeared.
“Nigga stole my bike” is a joke about Punchout. In the game, the running guy is the boxer who’s training, and the guy on the bike is the trainer, riding a bike to keep up with him. By adding the words “nigga stole my bike” to the tune of the game’s music, it makes it seem like the trainer is just some black guy who stole the other guy’s bike, so he’s trying to chase him down.
The “Nooooooo” thing is from some dumb Adult Swim show, Metalpocalypse or someething.
Afte Numa Numa is something from “Phoenix Wright, Ace Attorney” a Nintendo DS game from Japan where you’re a lawyer or some nonsense. When an objection is made, a small bit of fanfare in anime style is had.
Peanut butter jelly time is one of the oldest memes out there. Give it a google.
Right after that is a clip from the Sonic the Hedgehog cartoon. Don’t know the significance.
After Star Wars Kid is a guy called “techno viking,” a not-as-popular meme, but one of the earliest.
“The balls are inert” is also from Dragon Ball Z. It’s funny because… balls.
Some corny Bollywood dance scene that hit the tubes a while ago.
After that I’m mostly lost. There’s the “O RLY?” owl, which is kinda self-explanatory, and a half-second shot of “Weegi”.
Most hyper-popular memes get documented here: http://knowyourmeme.com/