I've been modding Casio and Seiko watches for years now to help have a creative outlet. About 11 months ago I started filming the builds because I noticed people on reddit asking how certain things were done.
Three income streams came out of it that I thought was pretty interesting.
First one is commissions. People see a build and contact me asking if I'll do one for them. This brought in some extra change and helped me fund new build for the channel. Commissions and watch sales are hitting $500-600/month now in profit.
The second one is ad revenue, which is the part I find interesting. Currently it's sitting around $100 a month and a decent chunk of that comes from videos I uploaded months ago and haven't touched since.
The third one is affiliate revenue. In each video I link to the parts and tools I use throughout. This one started really small but now over the last two months it's grown to over $300/mo.
The workflow is simple and that's the main thing I'd want anyone to take from this. I'm filming the thing I was doing anyway. Actual video editing consists of cutting out the dead space, so the silences, me fumbling for a tool, the bit where I drop a spring bar and spend four minutes on the floor looking for it. Then I record a voiceover on top of what's left. Thumbnail, title, upload. No script, no second shoot, very little b-roll. For a full video it takes an hour or so.
Overall it's getting pretty close to $1000/month and while it isn't life changing it helps fund a hobby I love which in turn slowly increases the money I make. It's also not instant and the first handful of videos made basically nothing for a long time, which I'm guessing is where most people bail.
The reason it worked for me is that the filming attached to something I was already doing. If I'd had to go find a hobby to film I don't think I'd have lasted more than three months.