Is one actually participating in the incident?
No it is a recording, you do not take on the karma of the criminal or the victim.
You only gain knowledge that the event occurred.
Does it add to one's karma?
How you react to the video determines the karma acquired from watching the video.
- Empathy and compassion for the victim?
- Joy and pleasure in watching the crime
- Detached indifference
- With the motivation of trying to increase security / prevent crime by learning about such
These are just some situational conditions, reasons for watching, and reaction to the video determines the karma. Each has its own separate effect.
If we ignore the video , are we creating a bigger incident?
This is situational as well. Is it a video of something we have no control over? If so the answer is no.
Is our job to stop crime, or does the video give you some knowledge that could stop the criminal etc. and you choose (Through apathy or other reasons) to ignore it, then the answer is yes.
However if it is a youtube fail compilation video, or just a compilation of random crimes, that have nothing to do with you, or your community, ignoring it, would be the best option.
By that I mean, not seeking more out to watch as well.
A side note : Seeking these videos out merely for self entertainment would not be participating in the event, but would in my opinion be negative karma. Watching movies is one thing, they are fictional, but when you are at a point where watching real world people suffer at the hands of others is what you need for entertainment, I do not think there is any way you could say that you are accumulating good karma. Though you are absolutely not accumulating the same kind of karma as the criminal, the kind you are accumulating would not be favorable.