Post Production- Editing

Whilst i was editing my movie together i decided to add a green screen effect so i had to download the clip and drag it into my timeline. I then went into the effects panel and selected the effect called "ultra key" and dragged it onto my green screen clip. This then removed all the green within the clip so i just trimmed down the clip to the length i wanted it and made it fit perfectly into the scene i wanted it. The only problem i encountered whilst editing this effect into my movie was ensuring it lined up perfectly with the beat and the movement within the scene to increase the tense atmosphere that the scene was omitting.