Nautilus, the file browser that comes installed by default in the GNOME environment, supports preview files when placed a cursor on the file’s icons. In the case of the videos, it shows a random frame on the icon, the first lines of the document in a text file or the actual preview image if a graph.
For Ubuntu there is a package called OpenOffice Thumbnailer with which also activates the preview icons of documents in the office suite from Sun. Only need to download the DEB file (from Launchpad) and install it by double clicking it. Once the session is restarted GNOME icons for OpenOffice.org files should appear with a preview of each document.