Is there a way to use transparency for an object using the keyframe? (my situation here would be not to use the handle of transparency because it is not gradual in an interval/clip) If not, is there any effect or way to do this using resources from the effects tab?
Is there a way to use transparency for an object using the keyframe?
Yes, it's just not in an obvious place. Select the object, Effects, Video Effects, Chromakey, and adjust the Video level slider. You can keyframe this.