I put the 40 STM, 50 STM and 18-55 STM together to see with a subjective test of noise and the 40 STM was by far the noisier. The 50 STM was still noisy, if you can hear it's motor audibly without effort, it's noisy in my book. The 18-55, I can't hear at all. My 35 F2 IS's USM knocking around is more audible than the 18-55 STM (that's nuts!). I imagine many of the STM zooms are dead quiet.
While these short STM primes have no place in this thread, the subject came up because of talking about STM in general, as the OP mentioned making the odd video here and there. I highly doubt the OP, just dabbling with an odd video, is going to have a full on video setup with an external microphone and all that, considering the natural of this thread (budget, etc). So the microphone will be on-camera, and it will pick up all noise. And STM lenses like the 40 & 50 are just too noisy honestly for that. I've tested it and it's really annoying. The 18-55 STM was so quiet, it made sense, "ahh, that's why they made this." I imagine many other slower STM zooms are also dead quiet and good for this. But these short fast prime STM's are definitely not quiet. TeamSpeed dragged in the Vlog, external mics, etc, for whatever reason to comment on the noise of the 40/50 STM's after stating everything after the 40STM got better, but the 50STM isn't much quieter, so maybe that's why it came up. But it's clear the OP will not be doing that, and it will be on-camera microphone, and the 40/50's are noisy for on-camera microphone for someone who's not already big into audio processing and video to begin with (OP clearly is not).
I'm very curious to hear the difference between the 18-55 STM, 18-135 STM, 55-250 STM and 24-105 STM. If they're all dead silent or not. I bought several of the STM's just to see if the silence was legit and was sorely disappointed by the 40STM & 50STM in that regard. Sold the 40 STM and kept the 50 STM as it's a great little lens, just not silent. Bought the 18-55 STM just to see, and was surprised it was so quiet, dead silent. I'm curious about the others now. Granted, I don't do much video, especially not with AF lenses and telephoto (I mostly use manual fast primes for video). But for the sake of the "dad at an event recording it as video on the dSLR with an STM lens" argument, I'd be curious to know.