The problem with these videos is that people don’t start recording them until they notice something is “happening.” What led up to the “something” in the time before the witness took notice of it, got his phone out and started recording is never clear.
It’s not a problem, it’s just information that’s incomplete. More information is better than less.
There is no problem with incident video, because any piece of video evidence is better than no evidence at all.
Many times the LE video is not complete or out of their field of view. Other times LE will obtain video from non-LEOs to obtain valuable evidence like when that machete swinging ding who was hacking at passing vehicles in the Oakland intersection recently.
Video is a good thing and it's also starting to keep cops in line where they once would cross that line as a matter of routine. In fact a lot of LEOs have been caught on video doing things they shouldn't be doing like stealing cash during a robbery /burglary investigation.
I use audio/video which is fed to remote servers in real time. It's very good cheap insurance, not only for possible bad cops with heavy badges, but for anything else. Ya got to be careful out there. LE better get used to this because it's certainly everywhere and it's not going away.
If someone puts up a video on youtube which does not cover an incident from beginning to end, that's the way it is. In fact most video ever taken of any incident does not cover the entire incident. Just look at the news. It's just the way it is.