Your video or animation can be previewed in the document window. Photoshop uses RAM preview to preview the video or animation during your editing session. When you play or drag to preview frames, they are automatically cached for faster playback the next time they’re played. The cached frames are indicated by the green bar in the work area of the Animation palette. The number of frames cached depends on the amount of RAM available to Photoshop.
In the timeline, drag the current-time indicator.
Use the playback buttons at the bottom of the Animation palette.
Press the spacebar to play or stop the playback.