What controls are there in the built in player? While using the F11 Play Rendered Animation window, I have noticed that when you click or press any keys it will pause automatic playback. This lead me to the question,  what controls are there? Is it possible to start automatic playback again?
A - toggle frame skipping.

P toggle ping-pong.

↵ Enter start playback (when paused).

Numpad 0 toggle looping.

Numpad . manual frame stepping.

← step back one frame.

→ step forward one frame.

↓ step back 10 frames.

↑ step forward 10 frames.

⇧ Shift+↓ use backward playback.

⇧ Shift+↑ use forward playback.

⇧ Shift hold to show frame numbers.

LMB scrub in time.

Ctrl++ zoom in

Ctrl+- zoom out

F flip image on the Y axis

Shift+F flip image on the X axis

I show frame indicator

Esc quit


Playback speed

1 NumPad 60 fps
2 NumPad 50 fps
3 NumPad 30 fps
4 NumPad 25 fps
⇧ Shift+4 NumPad 24 fps
5 NumPad 20 fps
6 NumPad 15 fps
7 NumPad 12 fps
8 NumPad 10 fps
9 NumPad 6 fps
/ NumPad 5 fps
- slow down playback.
+ speed up playback.

See also the Blender manual.