[Only works if you have a geforce graphics card]
So if you are going to fill out a player report it says you must have some kind of evidence whether it is screenshots or a video.
If you have a geforce graphics card you have most likely heard of shadowplay: http://www.geforce.com/geforce-experience/shadowplay
You can set this up so that is is temporarily recording in the background while you play and it causes a very small frame drop, nothing very noticeable.
Without shadowplay on I run arma at a solid 60fps, with it on I run around 55-60fps. You can set this up so that with a press of a button, the past 5 minutes (or however many minutes, you can change this) will be saved to your computer. So if you ever end up getting rdmed just press the hotkey and you have all the footage.
Here are some screenshots:
http://prntscr.com/66uhg5
http://prntscr.com/66uhz1
http://prntscr.com/66uice
http://prntscr.com/66uju8
You shouldn't use this tool just for catching RDMers and things like that. It is a great recording device overall. Obviously it has a non-shadow mode where you can start the recording manually and end it manually. There is also a manual recording/shadow setting which allows both at the same time. So you can save the last 5 minutes of action and begin manually recording!
The quality comes out great, even at medium quality it is 60fps and it looks amazing.
I hope someone found this effective!