I haven't watched the video yet, but just because it's relevant to the topic...
I used to stream to Twitch with just ffmpeg. No OBS or anything.
I mostly did speedruns, and I needed a timer, so I wrote my own. I had ffmpeg read the current time to display from a file in /tmp/
and had a Go program that would write to that file at the same rate as the framerate at which I was streaming. Worked really well, actually.
I also made some videos (mostly tutorials for pulling off certain glitches in The Legend Of Zelda: Breath Of The Wild) and put them on YouTube. I edited those entirely with ffmpeg and a pretty simple Bash script.
I'm definitely not going to claim they were what you might generally recognize as "well-edited" videos, but they did the job. And I definitely wasn't really looking to "make it big" on YouTube or anything, so I wasn't looking to polish my videos.
Here is one of my videos for reference. And here is a clip of a VOD from one of my streams that demonstrates the timer I mentioned.