user8010: Example: I have a clip of 2 mins in my timeline and I only want to add blur effect to certain length (say 45 seconds to 50 seconds) of the clip.

user2836: In addition to KC McLaughlin's suggestion, for something like blur, you can keyframe the amount of blur to apply.  This allows you to do some interesting things like have something go from clear to blurry and then back to clear smoothly rather than suddenly being blurry.
You can also emulate what KC was saying by putting two keyframes one frame apart, but honestly, if you want it to just turn on and off instantly, cutting the clip up is probably the easiest approach unless you are going to be moving the clip around a lot.

user6671: The easiest way to do this would be to cut your clip where you want the blurring effect to start/end.

8010: <p>Example: I have a clip of 2 mins in my timeline and I only want to add blur effect to certain length (say 45 seconds to 50 seconds) of the clip.</p>
 2836: <p>In addition to KC McLaughlin's suggestion, for something like blur, you can keyframe the amount of blur to apply.  This allows you to do some interesting things like have something go from clear to blurry and then back to clear smoothly rather than suddenly being blurry.</p>

<p>You can also emulate what KC was saying by putting two keyframes one frame apart, but honestly, if you want it to just turn on and off instantly, cutting the clip up is probably the easiest approach unless you are going to be moving the clip around a lot.</p>
 6671: <p>The easiest way to do this would be to cut your clip where you want the blurring effect to start/end.</p>
