You can take a look at an LC filter sold here on HK as that will help reduce noise in your FPV setup. Depending on what model filter you get, it may interfere with your OSD so you may want to get one that HK does not offer here yet. that way you can bridge the connection and change it to work for your OSD.
"It is now possible to select between common mode and differential mode filtering. A solder jumper pad on the input side disables filtering on the negative/ground-lead. If you experience issue with OSD systems, try changing the filter to differential mode."
I am researching the same thing now!
They certainly do. They are quite common these days on all sorts of electronics. It's not a written guarantee that it will stop all noise but UBECS, ESCs etc throw out heaps of rubbish and ferrite is great at decreasing it. There are other reasons for servo jitter. pushrod binding, full throw of the servo, antenna too close to the ESC or UBEC and so on. Try decreasing servo throw by 10% and see what happens. It cured a few of mine. Good luck.