Open your time-lapse video in your preferred video-editing program. Although each program may vary when it comes to the exact name and location of its buttons and functions, the basic features typically include speed-altering effects that allow you to slow down or speed up the playback of your original video footage.
Drag your time-lapse video from the "Project" or "Import" window to the "Editing Timeline." This part of the editing interface is where the actual editing process happens. The timeline features a number of audio and video tracks where you place your sound and visual elements.
Select the program's "Speed" feature. This is typically under a specific menu program like "Video" or "Video Effects." Most programs also allow you to alter the speed of a video by right-clicking the actual clip from the "Editing Timeline," then choosing the "Speed" or "Duration" option.
Select the speed you want to use from the window that appears. The default speed for your video is 100 percent. Choosing a percentage lower than this makes the video play slower, while a higher percentage makes the video play faster. Select a program that allows you to choose the time duration as an alternative to choosing the speed-change option, if desired. For example, you can instruct the program to play a two-minute time-lapse video for a duration of three minutes. The program computes the applicable speed to slow down the video playback into a three-minute footage.
View the edited time-lapse footage using the program's "Preview Window." If your program doesn't provide automatic or real-time rendering, you must first render the edited video before you can properly view it with the applied speed or duration change. Rendering refers to the process of generating a new image based on the effects or edit done in the video.
Export your slowed-down, time-lapse footage using your preferred video file format like AVI, MP4, WMV or MOV.