Each event is window into the media that is associated with the event. (the media is the AVI file of JPG image or whatever you have dropped onto the video timeline) Multiple events can share the same media. If you add a Video FX to the event. Only that event is affected. Any other event that shares the media will be unaffected. BUT, if you add a Media FX, ALL of the events that share the media will be affected because it is being applied the underlying media itself.

To test this, drop the same piece of media onto the timeline twice. Add a Gaussian Blur FX to one of the events and you will notice that the other event will be unaffected. Now add a Media FX of the Black & White 100% filter to one of the events, and both events turn to Black & White!

This is very useful if you have already split up your events and assembled them on the timeline and then realize that you need to do some color correction. You can color correct the underlying media and all the events will now be corrected.

~jr