Here's a little pictorial on LC filtering. I always use a piece of servo wire and strip off the signal wire so I'm left with BLACK-RED. For constructing the inductor (the L in LC filtering) I loop both wires through a ferrite ring as many times as it'll fit, but at least >5 times. I use both wires as that gives a little better attenuation of the ESC noise as the inductor now becomes a common mode inductor.
I then simply solder a 470...1000uF/16...25V electrolytic capacitor (the C in LC filtering) to the side that attaches to the audio/video transmitter and the camera. The capacitor is polarized, hence it has a + and - pole. The - pole is marked with a stripe and - symbols on one end, you can't miss it, that needs to go on the BLACK wire, the + pole is on the RED wire. This will clear up any ESC noise that normally causes lines in the video. The parts you'll need are:
- Length of servowire
- Ferrite ring
- 470...1000uF 16...25 volt electrolytic capacitor
Fig 1. Here's the parts you'll need, available from Radio Shack and similar stores.
Fig 2. Here's the servo wire being looped through the ferrite ring.
Fig 3. And that's the finished LC filter with the capacitor soldered on.
All that is required now is some shrinkwrap to keep the inductor tightly wound and to go over the exposed electrical contacts. That's it, simple yet effective and all that from a mere few $$$ worth of electronic parts.