From Push My:
RePlay is a super fun App that allows you to insert slowmo effect or fast-forward effect to your captured video or any video inside your device Photo Library. As a result, you will get a stunning super cool effect embedded in your video instantly. RePlay offers a very simple user interface for ease of use. User starts by selecting desired video from the Photo Library & simply choose the required speed adjustment by dragging the slider to the left for slowmo or to the right fast-forward.
User will then have to select the "BEGIN" & "END" time for the effect to take place in the selected video. For this process, user will be presented with a video player where user can Play, Pause, Stop, Forward, Rewind or drag to the desired time frame to set the effect's beginning & ending time as required.
That's all you have to do & RePlay App is now ready to process your video. Just touch "Generate Video" & the processing will begin. Wait patiently until it is done! Time taken will depends on the quality & resolution of the video source (RePlay App will maintain the resolution & quality of the video source). Once done, processed video will be saved in RePlay App's Document folder where you can also access this folder from iTunes (via iTunes App sharing folder). Within this App, you can select "Preview Videos" to bring up this folder & view your generated video.
Within this view, you can rename, delete & preview generated videos. All videos are presented to show the video name, date created, size of the video & the resolution of the video. In addition to these, via the "Action" button, you can perform lots of other useful tasks such as saving the videos into the camera roll, email, open or export videos in other supported Apps, Dropbox.