techniques - tv flicker/white noise effect

If you look at the bottom right hand corner of the viewer in FCP you'll see a little film strip thing with an A. Click on that and look at Render>noise and you'll get your white noise video. You'll have to get the satic elswhere. Maybe record some off of a tv or if you have access to a sound fx library.
The rest is up to your creativity. Maybe some quick cuts of the noise or something. it really depends on what you want.

I've made convincing audio static by totally overmodulating a sound clip, and then lowering its overall volume using a nest.

Zap

Yea. AE or Motion will be your best friend here for getting a real nice, stylized look, but it should be possible in FCP if those tools aren't available. I'm really not a huge fan of FCP's noise generator though, it looks too fine and generic.

I once achieved a nice effect by recording TV static, and playing it back through a broadcast monitor. There was no sync signal on the tape, so the image flickered and distorted as it was going into FCP. I then played with opacity and composite modes to blend it with the footage that was to sit under it.

If you want to distort the video that sits underneath it, consider finding some static that has a nice black/white contrast, and making a displacement map out of it.

good luck.

Bryan