The above video is just one of literally thousands of videos from space. A variety of the more extreme conspiracy theorist think that all footage from space (which in the last few years has almost all been from the International Space Station) is fake. They point to films like Gravity and the existence of zero-gravity planes as evidence how these things can be simulated.
Live video video like the one above (Rick Mastracchio and Steve Swanson live chatting with students at Boise State University in Idaho) is more problematic. The video clearly shows the astronauts in zero gravity for an extended period of time, with floating objects and people. How could this be faked?
The belief that something is fake leads people to postulate the most bizarre suggestions. In this case the theory is that the astronauts are suspended from the ceiling with invisible wires, and the floating objects (a ball, the microphone, and a baseball cap) are not actually there, but are 3D computer graphics added to the scene via some kind of augmented reality. The astronauts can supposedly interact with these object because they are wearing special contact lenses that allow them to see the virtual objects, and there's some computers tracking their hands. See this video for more details.
There's a number of problems with this theory. Firstly the idea that they are suspended from wires. At 11:00 into the video Steve Swanson performs a twirl followed by a backflip
In order to simulate zero G with wires, the person would need to be supported from multiple different points.
This would make it impossible to do the maneuver that Swanson does.
The idea of augmented reality is theoretically possible, but would require a level of technology far in advance of what is known to exist today. In particular VR contact lenses - we don't even have huge VR headsets that are capable of doing this, let along contact lenses. However super-advanced secret technology has always been one of those impossible-to-disprove things. So let's look at the actual evidence that these things are being used:
At 18:10 in the video, Rick Mastracchio reaches takes his hand off the grab bar, starts to clasp his hands together, then stops and puts his hand back on the grab bar.
The suggestion is that he is attempting to manipulate a virtual reality 3D object that somehow is not showing up in the video. The problem with that is the hand movements he makes are identical to the movements he makes through the entire video. He's constantly reaching for the grab bar, folding his hands, entwining his fingers etc. Here's a compilation of all these movements. All the conspiracy theorists did was take one that looks a little odd out of context.
Another claim is based on the video at 12:00 where an astronaut is seen propelling himself along the passage behind them.
There's some kind of strap on the back of his pants, and the suggestion is that this is part of a harness. A problem here is that's it's not taut, it's just sticking out there.
However, loose straps are a common feature on the ISS. Velcro straps are commonly used to fix things, and the astronauts have special pants with strips of velcro on them. There are several such things it could be, but in this case it looks like it's the strap on a bag, seen in this video.
The thing strapped to his leg is not part of a harness either. It's a clipboard. Seen in this video, and also with a loose black strap.
With this particular theory I think the best antidote is to look at he videos that show extended walkthroughs of the station, with astronauts performing motions that are impossible to simulate in normal gravity, and too long (and it too large a space) to be done on a plane. Here a great example:
Or this high speed tour of the entire station:
At 3:50 Gregory Wiseman floats the entire 350 foot length in one take.
There are also other live chats where the astronauts perform even more varied maneuvers, even more impossible to do live with wires.