Did you know that you can’t add a marker in the Sequencer/VSE while playing back?
No no no, you can only (dynamicaly) add them in the Timeline window.
This drove me nuts for ages! Playing along pressing “m” key madly with no result. Then creating a Timeline window and bang! Pressing “m” adds Markers in playback.
Shouldn’t I be able to add them in the VSE during live playback too!? After all I can add them from the menu and they appear after adding them in the Timeline window. Aaaargh.
Thanks for sharing.
It turns out that the little frame bar at the bottom of the VSE timeline IS active. So you must hover the mouse there and press the m-key.
Not very obvious.
Thanks. I’d given up on this. I’ve tried to cut to music a few times and just couldn’t grasp why I couldn’t tap in my markers in realtime.
Tell me about it, I like to cut to audio cues but was getting sick stopping all the time.
Excellent tip thanx for sharing! 
I had also given up on this…
Well good news, Mango people must have hated this too.
Revision: 44765
http://projects.blender.org/scm/viewvc.php?view=rev&root=bf-blender&revision=44765
Author: aligorith
Date: 2012-03-09 13:31:20 +0000 (Fri, 09 Mar 2012)
Log Message:Markers Tweak for Sequencer
Applied the keymaps hack which is used for other animation editors to allow
markers to be added and renamed anywhere from within the sequencer strips
region, instead of just when the cursor is over the scrollbar.
Other operations where the hotkeys conflict though (delete, move) can still be
done only from the scrollbar, or better still, from the Timeline.
ha ha…cool!
Mango’s paying dividends already!