Comment 2 for bug 592506

My video plays back fine, just slow because of the maxed out CPU.

In VLC, if you switch to advanced view of settings, you can that the option is under the ffmpeg decoding section. After some googling, I have narrowed it down to libavcodec. http://sites.google.com/site/linuxencoding/x264-ffmpeg-mapping look at the -flags +loop part. I am assuming that Openshot or MLT uses ffmpeg to play the preview of the project.