I agree about sleight of hand stuff, but nobody can hijack the cell phone network. Make phones ring, all on different network providers, at the same time, amongst dozens and dozens of people.
Well.... that depends.
There's two things that occur to me with this one.
First is this phrase: "Tech that can be built by the mind of man, can be hacked by the mind of man, no matter what it may be".
However, that's a giant recipe for legal trouble involving the wrath of giant corporations. If that's something that was involved here, it means someone on their team screwed up REAL bad in terms of ideas.
Number 2 is how it goes when cell phones are shown in all sorts of series doing impossible things, which is... they're not *really* running calls, or in some cases, they arent even really cell phones. I'll put it this way: Even I could make a program that simulates this sort of thing. It'd be a freaking ugly program, but hey, someone else could do the art bit to get the look just right. And anyone with enough tech/hardware knowledge, and a bit of resources, could make a fake phone (particularly if they have real ones available to use as shells).
"Phones doing spooky things" is a common element in horror stuff, so I've seen that sort of thing pretty freaking often. Smartphones are even better for it, because they have screens and can do more than just ring and produce a voice, so there's all that much more potential for using them to immerse the viewers in that much more.
But in an overall sense, I think the explanation for me personally isnt so much anything specific in any of these particular videos, but is instead this:
After so much time on Youtube, and after so much time on the freaking internet (which I often refer to as a "bastion of lies", because I've seen too freaking much) I find it incredibly hard to take videos seriously, that claim to be showing paranormal stuff, or things of that nature (well, to be more accurate, I find it hard to take ANY video seriously... probably why I stick to fictional stuff and never, ever watch non-fiction). It's just too darned easy to pull off a fake, and the related tech has advanced to the point where you barely need any money to do it... you just need the know-how. Fake devices, fake locations, making things seem to appear/disappear, changing the textures of objects in the scene, stretching/compressing... all sorts of concepts that frankly I cant even think of (as I'm not a filmmaker) are possible. And for those that DO have resources (money), getting people to show up for minor roles as "the crowd" aint exactly hard, nor is setting up a larger venue for it to take place in. It's even possible for someone with massive amounts of skill/resources to set up a production and make it 100% look like it was done by an absolute amateur (and if you're wondering WHY anyone would do that, I again point towards the horror genre on Youtube. Believe me, it makes a given series far more spooky/scary/intense, when done right).
If someone wants to REALLY spook me... do something right in front of me. Or tell me how to do it, and then I give it a try and it works and I just spook myself. Provided you can convince me that I wont tear a hole in reality in the process of trying it.
Ya know, the frustrating thing is, I'm not exactly the skeptical sort... I think a variety of things I've said in various places on this forum show that well enough. It aint like I dont believe in the paranormal. But the internet has forever corrupted videos for me, specifically. Regardless of whether they're related to the paranormal, or to the purely mundane... they're corrupted for me. Even if I were to, I dunno, somehow unlock the quantum potential of reality and learn how to teleport chairs around at will, I'd still look at any given video and go "Ehhhh... I dunno, they probably did this and this and this... all these filmmakers and their devious tricks". Thanks, Internet. Bah.