Perhaps I've mis-understood how the lenses are meant to work, but I find that local files or folders never show up in any of the lenses unless I've previously opened them. This is true for the file and the video lenses.
For background I've upgraded from 11.10 to 12.04 recently. My ~/Video and ~/Documents are on a seperate partition which mounts on boot.
I've tried some related fixes from jfgi
zeitgeist-daemon --replace rm -rf ~/.local/share/zeitgeist rm ~/.local/share/zeitgeist/activity.sqlite
but to no avail.