\begin{description}
\item[Play every frame] this causes every frame of video to be displayed even if it means that the playback of the video tracks fall behind. Most likely you will want this enabled because, after all, in order to edit you want to see each frame. However, if you are just watching a big video, you can switch to not play every frame so that you can at least not be distracted by slowness.
\item[Framerate achieved] the number of frames per second being displayed during playback. This is updated during playback only. The goal is to get as close to the frame rate as possible, even if Play every frame is not enabled.
\begin{description}
\item[Play every frame] this causes every frame of video to be displayed even if it means that the playback of the video tracks fall behind. Most likely you will want this enabled because, after all, in order to edit you want to see each frame. However, if you are just watching a big video, you can switch to not play every frame so that you can at least not be distracted by slowness.
\item[Framerate achieved] the number of frames per second being displayed during playback. This is updated during playback only. The goal is to get as close to the frame rate as possible, even if Play every frame is not enabled.