Go for it. Video evidence can make a significant difference in compensation and who pays for injuries. The problem with relying on eye witnesses is (1) they're unreliable, (2) testimony depends on who the authorities choose to interview and which questions they ask, (3) if only the parties involved in the accident are witnesses, they may not be reliable due to shock, injuries, etc.

Without video evidence, anything an injured victim says immediately after an accident may adversely affect their compensation. For example, it's not unusual for victims of head injury to deny any problems (Google "head injury and lucid interval"); and victims of other physical injuries may not realize the extent of their injuries until later. This happened to me 15 years ago after a serious wreck caused by another driver running a red light, cracking several vertebrae in my back and neck and permanently damaging the C2 -- the full extent of the longterm injury wasn't apparent until days or weeks later, after I'd already spoken with authorities and the adverse insurance company under the effect of concussion.

And just this week I had a very minor crash -- more of a slow motion flop over -- with no scrapes or apparent injuries for almost 12 hours. I popped up, straightened the handlebar and rode 15 miles home without any apparent physical problems. But I woke up with a very sore tailbone where I'd apparently caught myself. Nothing serious, not even an apparent bruise, but it did remind me that the human body does a nice job of protecting us from the effects of immediately experiencing pain in order to enable us to escape danger. Later, after the adrenaline wears off and swelling begins, we being to experience the real pain.

But video evidence can be unambiguous and may offset statements made under duress or the effects of shock, concussion, etc.

Keep in mind that, depending on your state laws, liability may be limited to whatever your state's minimum liability insurance covers. This may be nowhere near the actual cost of the injuries and property damage. Unless the responsible party has deep pockets or was working for a business (presumed to have deep pockets), you may still bear the burden of most or all costs for an accident and injury that you didn't cause. So, again, why not go for the video camera as a buffer, especially if you're responsible for a family? Just makes good financial sense from that perspective.