There are a couple of points that I feel are worth mentioning in regards to dashcam use. It's likely that these will be increasing points of discussion as dascams become more unbiquitous.
Regarding the posting of every mistake other drivers make: One of the first things a new dashcam owner tends to do is start posting every little blunder, mistake and perceived slight by other drivers onto Youtube/Facebook/Reddit/Twitter for the world to see. These videos are generally boring and uninteresting - after all, most of us see plenty of that type of thing every day in real life - why do we need to see more of it from someone else?
More importantly, everyone makes mistakes and bonehead moves on the road, you and me included. If everyone had a dashcam and was inclined to be so vindictive, all of us are going to be showing up on Youtube/Facebook at one time or another. If another driver does something outrageous, that's one thing. I'm just suggesting that some discretion, courtesy and grace be used in regards to your fellow motorist. I would suggest a general rule: if you post other drivers' mistakes, you should post all of your own as well.
As a show of good faith, I removed several of my own dashcam videos that I had posted of drivers running red lights, pulling out in front of me and making other mistakes. In the future, I won't post anything of that sort unless it is visually outrageous or causes an accident.
A dashcam's video testimony goes both ways. Your dashcam doesn't just capture the actions of others, it captures your own as well. As dashcam popularity increases, the odds you're going to be on someone elses' camera also increases. I actually think this will be an overall good thing for society, as it will make more people think twice before making a stupid or aggressive move. I think of how less likely a road rage-prone person will be to act out if they know there is a good chance everything will be captured in 1080p high definition!
Dashcam videos are, by default, copyrighted by their respective owners: Someone who spent the money on a dahscam and installed it in their vehicle is the sole rights owner of any video that camera captures. Taking dashcam videos from around the internet and re-uploading them in compilations to Youtube, Facebook, or any other video service is copyright infringement and is illegal! Many unscrupulous channel owners do this and get away with it for a time, but this does not make it right. Some dashcam owners may be OK with their videos being used, but some may not be!
The original owner of each video has the right, by law, to issue a DMCA takedown if and when they discover an infringing copy. It is wrong for a compilation maker to take traffic/views/subscribers away from the original owner of the video. If the goal is to share new dashcam videos from around the internet and on Youtube, consider using playlists that link to the original video, or even a Facebook or Twitter page to share the links to the originals. The only proper and legal way to make compilations is to get explicit permission from every video you want to use.
"Fair use" is often claimed by compilation authors, but this is a weak argument at best. The compilation maker is going to various channels and taking what is often the original owner's most popular video, which is then used in a competing video that can and will go viral instead of the original. This isn't fair use in any sense of the word. Compilation makers who operate this way should be prepared for DMCA takedowns, shut-down channels and even copyright lawsuits from the original video owners. Any "fair use" defense will have to be proven in court, stating it in a video's description means nothing.