Finally I found solution of problem of eating standard hotkeys by Adobe Flash. It is extension/addon Focus Regainer. It works both in Firefox & Seamonkey. It work both on Linux & Windows, and maybe on Mac OS X.
Focus Regainer allow you to use standard hotkeys when focus is within flash plugin:
1) Ctrl+T
for open new tab
2) Ctrl+W
for close current tab
3) Ctrl+R
for refreshing page
4) Ctrl+Q
for quit Firefox
5) Ctrl+L
for focus URLbar/awesomebar
6) Ctrl+N
for open new browser window
7) F11
for fullscreen mode
and other.
In Mac Os X you must use Cmd(Meta)
button instead Ctrl
.
If single pressing of some hotkey does not work, then you must use double pressing. It is Adobe Flash plugin limitation.
Alternatively you can use hotkey Ctrl+Esc
or Ctrl+F12
to remove focus from embedded flash. Alt+Esc
or Alt+F12
are for moving focus back to flash object, but not always work, e.g. because html page can have multiple flash objects.
P.S.: Technical information about problem in my question with eating browser standard hotkeys is in Mozilla Bug 78414.