Actually capturing DoomRL and having it look good has long been a barrier, or I would have done stuff like this long ago. Finally I found Open Broadcaster Studio (OBS). Not only does it do a great job, but it's also freeware, can be used for streaming, and you can capture your face with a webcam while playing the game.
It does crash sometimes though :(
In the case of this video I decided to record the game, then after I was done playing to sit down and watch the video while commenting on it. I did it this way because DoomRL demands so much attention I'm not confident that I can talk coherently while playing it.
Yet.
I am getting better at this sort of thing. But I've still got a long way to grow.