Nope; none of them are. Though I don't fault you for thinking that; a lot of work goes in to making them feel "authentic" to viewers.
#1: PewDiePie is part of Polaris, which is the gaming sub-brand of Maker Studios, which is owned by Disney. He's also the top grossing star on YouTube for the last few years, and you don't stay king without a lot of marketing support.
#2: HolaSoyGerman is owned by Machinima. Machinima is relatively independent from big media (ignoring a $30M investment from Google), but they're still a major player in the YouTube world.
#3: Smosh is a huge enterprise, a YouTube brand in itself with dozens of sub-brands. It's the "juvenile humor" brand of Defy Media, which is owned by Viacom.
#4: This one was basically a PSA done by an actor / comedian / media personality. He likely had professional help making the video though (or is involved in video production work himself - not unusual for lesser known actors). But this one is a flash-in-the-pan viral video unless he can spin it into a production deal (though it wouldn't surprise me if he had already).
#5: Jenna Marbles is also part of the Smosh empire, though her deal looks to give her more independence with branding than most. But still, I guarantee she's not editing and posting videos herself.
All 5 of these videos were created by professional entertainers; 4 of them are the product of some YouTube media empire or another. It doesn't seem that way looking at the videos, but that's the entire point - it takes a lot of work to make something look low-budget yet still have high enough production value to be watchable.
The point remains though; you don't get a top viewed video on YouTube without significant paid advertising to support your channel. And most of the companies doing this advertising support are owned by traditional media companies.