Comment 12 for bug 185928

As I understand from the Totem FAQ, space cannot be used as an accelerator because it's reserved for activating regular user interface elements for accessibility reasons.

Citing from http://projects.gnome.org/totem/#faq:

Q: Why doesn't the space bar work to play/pause in windowed mode? It only works in fullscreen, and sometimes in windowed mode.
A: The space bar will work in fullscreen. But when in windowed mode, for accessibility reasons, we cannot use the space to play/pause (it is used to "push" buttons already). It will work sometimes, as the play/pause button, or the video widget might be the one with the keyboard focus. Try using "P" to play/pause instead.

The proposed patch hurts accessibility.