Space or Pause keyboard button - stop or resume playing;
Alt+Right or the Play toolbar button – plays the current video file forward at normal speed;
Alt+Ctrl+Right – plays the current video file forward at 1.5x speed;
Alt+Up, Alt+Down – stops the video playback.
Alt+Up or the Next Frame toolbar button – moves the video one frame forward. If used during playback, stops the video and if repeated moves it one frame forward;
Alt+Down or the Previous Frame toolbar button – moves the video one frame back. If used during playback, stops the video and if repeated moves it one frame back.
F4 keyboard button – jump to the current subtitle's in-cue, play the subtitle and then jump back to the in-cue. Helps to verify that the subtitle is well positioned during its whole duration.
Increasing and Decreasing Speed
Alt+Shift+Down – reduces the playback speed;
Alt+Shift+Up – increases the playback speed.
Fixed Speed Commands
Ctrl+Alt+Right – plays the video forward at 1.5x speed;
Alt+Shift+Right or the Fast Forward toolbar button – plays the video forward at 8x speed;
Alt+Shift+Left or the Fast Backward toolbar button – plays the video file backwards at 8x speed.
Jump Backwards and Forwards
Alt+Backspace – jumps back 10 seconds and starts playing forward at normal speed;
Alt+Shift+Backspace – jumps forward 10 seconds and starts playing forward at normal speed;
Go to Previous/Next Shot Change
Alt+[ – go to previous shot change;
Alt+] – go to next shot change;
Home / End
Alt+Home – jumps to the first frame of the current video file preserving the current playback speed if the file is being played forward;
Alt+End – jumps to the last frame of the current video file and stops the playback;
The jump interval for the first two commands can be changed by using the options in the Preferences menu.
For quick navigation through the video file you can also move forwards or backwards the red "position bar" on the Timeline.