Well having watched the netflix series, this is what I took from it... The most terrifying thing discussed in the documentary is the obsessive "web sleuths" who think they can solve a murder by going through whatever they can find on the internet and essentially making their own truth up about it. They think whatever's on the internet is all there is to know, and obviously they don't know what the police know. In their efforts to Find The Murderer they picked this poor Mexican death metal musician who'd stayed in the hotel, decided he looked weird and the lyrics he sang was a confession - and then he got death threats from all over the world. Eventually he tried to kill himself. And he said he hasn't written any music since. This poor bloke, caught up in this case by complete idiots who think their opinion has got to be correct, and blast it across the world.
They didn't know Elisa Lam had already had many weird episodes at home with her bipolar disorder. And she hadn't been taking her medication properly (as shown by the autopsy analysis). She'd also been behaving weirdly enough for it to have been noticed in several places she'd visited in LA (being thrown out of places for it), and she'd been leaving odd notes in the hotel and the management moved her out of a shared dorm there. And as for that lift video, to me, without a doubt, she is acting weirdly (she doesn't just get in the lift and press a button, does she, which would be "normal") with all that skipping about and hiding and elaborate hand gestures. There were no signs she'd been attacked. And the hatch on the water tank was open so there was no need to think someone had shut her in there.
But the 'web sleuths' had heard the hatch was shut (from some casual remark from a policeman) and so they Knew she was murdered, and all their sleuthing was based on that. Plus in a frightening way they look for conspiracy everywhere. Some of the connections they make are really stretching the bounds of credibility - you really have to watch the programme to believe it! But I guess on internet forums things get turned into fact. Yes there are some pretty weird coincidences by the sound of it. But you can see how easy it is for some people to make 2+2=5. (like the claims against the musician above).
It makes their lives more interesting, they spend 100s of hours poring over the stuff. (And maybe I'm a bit like them for being interested in these unsolved cases too. Which is not a good thought really!) I suppose it's a human nature thing (of wanting to make sense of things that don't make sense) but taken too far. Which is kind of interesting from an anthropological fortean way. But with potentially ghastly consequences.