You know, I never thought about using my device for this purpose, but instead of using a key fob, how about looking at my device by the Security company Swann…
It’s basically a ball point pen with a hidden camera just above the clip. You can take both video and still photos. It comes with a disk to edit the images, but I use a trial programme for free called Camtasia by TechSmith (Google it); and just reinstall it every 30 days, lol. 
Sure, there are two tiny lights on the back, but they can be hidden with a bit of tape.
All you need do is hit the button on the top; and you’re recording. The quality is really good too.
I have to say from watching the 1st 3 videos, there is signs of hits, not too sure about the 2nd one though, hard to see the eye contacts and the text seems a little blurry. It says x2 ammo and x3 IS, what strengths; and is it the bottles or the 2-go range?
That 4th video, haha I love it. Big question is, is this guy wearing mones, or is he just getting hits because of his build/friendly nature?