I suppose I'm asking a bit much of a 6 minute internet video, but perhaps a bit more in-depth analysis of this problem would make more sense?
As both a video game and CCG hobbyist, I get to spend a lot of time on forums like this one talking about the things I love, and I am familiar with phenomenon of which Jim speaks, and I'm pretty sure I know why people are being serious. They're being forced to.
Head #1 of the Hydra: The Internet
This is the Internet, and 15 years ago, when it was the Wild West of communications, pretty much no one cared what level of crazy you were. These days, people have cottoned to just how much information is available on the Internet, and with debates happening everywhere as fast as the electrons can carry them, people are getting more used to malarkey being shoveled, and now have the tools to fight said malarkey. So any claim on the Internet may come with a tacit or explicit 'show your work' in order to be 'taken seriously.' I know I've caught myself reflexing hunting for proof before I make an opinion post. I can't imagine I'm alone.
Head #2 of the Hydra: Dicks
There are some people who will say something and then try to get away with their faux pas by claiming that they're kidding. I don't tolerate these people IRL, and I imagine broad stretches of the Internet are the same. I've watched people get swarmed with reports when they intend some lighthearted satire, and the mods capitulate just to shut the mob up, because to some, they are indistinguishable from people being dicks.
Head #3 of the Hydra: Console Wars
I'm sure you know what I mean. People like to be on the winning team, because it gives them license to be a dick to the losers, and that's something we all want: to be dicks, occasionally. Console manufacturers stirring that pot for press is obnoxious, but understandable.
Head #4 of the Hydra: The nature of comedy
I haven't tried especially hard to be a comedian in my life, but I do try to be funny where I can, and I've noticed that unless you specifically cordon off where the comedy is happening, some people won't get it. Notice how the reaction to flash mobs is typically confusion, rather than amusement? That's because people didn't know they were past the comedy tape. Once they're aware, then the laughing starts. If someone doesn't feel something is funny, they may have moved the comedy tape. There's no saving it, then. Worse still, if someone steps outside the comedy tape, they can occasionally move others to do the same.