First because they didn't know they will be abducted.
Second I am sure that alien technology is more advance. So if I ever put a video camera on my bedroom and get abducted, I don't think that the video camera can actually provide a solid proof. Because in our time now, anything is possible with computer effects, and editing soft wares. Unless I could provide substantial evidence to prove alien abduction, and circumstances where in scientists and skeptics will have a chance to cross examine my proof. Then lucky me.
Third, scientists and researchers now haven't even proved yet that they really exist or prove that there is life in mars. Because that is the closest thing to possible that there are really aliens.
Despite that the UFO sightings, and news about aliens in the past, those aren't enough to say that they really exist. I want to believe that they do because of the news. I mean there wouldn't be a news if nothing really happened. Only the problem is, no one could really explain what really happened in the past, if there are real alien disc space ships. And scientists still can't explain Star child. Who is really alien to me.
Another thing, I don't think I'll see something clear on the videos since alien abductees will experience loss of time. For example there is a loss time of 10 minutes. It would be something like this. I'll watch the tape, let's assume I started recording by 9:03PM and got abducted and was returned after 10 minutes. If I watched the tape, the tape will start by 9:03PM and will jump exactly to 9:13PM
I don't have any abduction experiences, my example is based on a small books that I've scanned months ago about alien abductions in the past.