Yeah I would like to see this too.
I don't know if this exist but I've thought about this a couple times, A screen recorder program that records 3 minutes or lets you set a time, then starts recording over it's self from the begging unless you tell it to keep recording. So if you want to record something just in case something interesting happens, you just hit record and will continue with the 3 previous minutes added. I thought about this a couple years ago, I just wish I could actually make it.