And JanDarby, what you're suggesting is that one of the characters should not want to watch the tape.
That was just an example to bring in conflict, b/c that's probably why you're struggling over the video scene: there's no conflict (b/c the characters are NOT struggling with anyone in the here and now).
What you've got basically is:
Protagonist's goal: to see the tape
Antagonist's goal -- there is no antagonist, since all the other characters agree with protagonist's goal, so there's no conflict.
What you need in the scene is:
Protagonist's goal: something that is opposed by someone else
Antagonist's goal: the opposite of protagonist's goal.
ANother possibility, so they're not fighting over the tape, would be for the husband or wife to have the goal of convincing the SIL she was attacked, and her being in denial. They all agree on watching the tape, but for different reasons. Then you'd have:
Protagonist's goal: to prove SIL was attacked
Antagonist (SIL in this scene): to prove she wasn't attacked
So, they play the video, and comment on it, with the SIL in denial until she ultimately has to accept the facts.
But I don't know if that's where you're headed, so forget my examples and look at what you're trying to do with the scene and consider where the conflict could be. You, the author, have certain facts you need to reveal: 1) wife's attack, 2) husband's causing the attack on the wife by turning on the machine, 3) the SIL's attack and 4) the husband's past attack. (Note that what you are trying to accomplish and what the POV character is trying to accomplish are two separate things, and you need to make sure to distinguish between them and then resolve both what you want done and the character's goal.)
The things you as the author are trying to establish are all "incidents" and plot points, but they're not scenes. They're things you want the reader to know, and you're a good enough writer to know you can't just tell the reader: "the husband turned on the machine and the wife was attacked by a demon, causing the SIL to come running out of the house ..." etc. You're going to show all of that. Which is good.
Now you need to go one step deeper and show the facts that you need the reader to know, but in a context that the reader will want to know them, and that means that the pov character also has a goal for the scene, and there's a struggle going on, and the reader is thinking (on a subconscious level if not a conscious level: "Will the protagonist accomplish his/her goal for this scene?" or, more specifically, "Will the wife escape the ghost?" or "will the husband figure out where the ghost is" or "will the SIL acknowledge her attack?").
It's not enough to just show the incident; it needs to be presented in the context of a struggle between characters. Otherwise, it's just random stuff happening, rather than plot; they're incidents (things the author cares about), rather than scenes (struggles between characters).
Think about the incident of watching the video and imagine it playing out on a stage: You've got a bunch of people looking at a video. The actors' faces are going to reflect their emotions -- perhaps guilt by the husband, horror by the wife, denial by the SIL. But that's all that's happening. A bunch of people sitting around and watching something horrible that's done and can't be changed. They're not arguing about it, they're just sitting and watching it. Not terribly riveting stuff to watch, when there's nothing the characters can do about what's happened. And now, switch to your written version, and add in the fact that the events have already been shown in real time in the previous scene. Why would the audience/reader want to sit through it? YOU want them to care about the characters' response to it, but the way to do that is to establish a scene question -- will the protagonist do X or not -- and then the reader will care enough to keep reading, so you can reveal the facts and emotions you want revealed.
You've got to give the readers a reason to keep turning the pages. If the protagonist's goal at the beginning of the scene is to look at a video and find out what happens, and everyone in the room is happy to do that, there's no reason for a reader to worry about whether the video is going to be played. It is.
You can't assume they'll care, just because you do, just because you, the author, knows that what's happening is important. (That's a different, implied version of telling instead of showing: "keep reading, and you'll be glad you did," versus simply giving them a reason to keep reading.)
The reader only cares if you give them a reason. And that means conflict. In every scene. Figure out, not just what you want to accomplish as the author, but also what the protagonist in the scene wants to accomplish. The reader doesn't care what you as the author want, but (we hope) does care about what the protagonist wants to accomplish, as long as there's some question about whether the protagonist will actually accomplish his goal.
JD