How do I move keyframes in an FX/filter so it only affects part of the clip?

[nickmoon]

Struggling for ages on this one. Probably a dumb question.

I have a long video clip (10sec to a minute) and I want to apply multiple effects at different times in the clip. I thought I may be able to do this by moving the start and end keyframe around in the FX/filter settings but that doesn't work.
Are there any good tutorials on this if it is possible?

I can split the clip up but the probably with that is its inflexible when I want to move the FX around to sync with the music or soundtrack.

Thanks