The upcoming KPhotoAlbum has support for categorizing videos along with its usual support for categorizing images. Getting KPhotoAlbum to show thumbnails for videos and actually showing the videos can be tricky. This page will give you some hints.
KDE has packages for generating the thumbnails for videos. If the correct packages are installed then you should see the thumbnails. Below is a list of packages required for different distributions:
Note for Ubuntu users : Ubuntu is a Debian which has been slightly modified (apt-get for example, is the killer-app coming from Debian). So maybe try the Debian advice below if you can't see videos on your system.
Note : if I install Kaffeine in addition, then KPA opens a black screen with just the sound for the video, and next time I open the search dialog, KPA crashes violently. Simply removing (apt-get remove kaffeine --purge) Kaffeine worked just fine for me.
(In Ubuntu 8.04 Hardy, it's kmplayer-konq-plugins that you need to make video playable.)
The real problem with the thumbnail package which comes with KDE is that they take the first image in the video sequence and uses that as the thumbnail. This is often just an intro screen which do not reveal the content of the video. An alternative is MPlayerThumbs which works great with KPhotoAlbum.
KPhotoAlbum will show the videos in the viewer if the right support packages are installed (Again KPhotoAlbum doesn't do the real work of showing the videos, but relies on the KDE subsystem to do so. Below you can see which package are needed for your system:
If you believe you have all the right packages installed, and it still doesn't play videos, then itis time to check your KDE configuration.
Open up Konqueror, choose Settings->Configure Konqueror and choose the File Association tab. Open up the video branch, and choose the item you can't get working (e.g mpeg). The screen show now show a tab widget for configuring that item. First check that the extention you have in mind is listed in the Filename Patterns.
Next choose the Embedding tab, and check that it shows any services in the Service Preference Order listbox.
One way to get to this page is from trying to play a video, with the result that KPhotoAlbum shows you an error box with the different actions it tried before failing. Here is a list of the errors:
If any of these fails it is very likely that you need to go back up and look carefully at the settings in the previous section. If you see one of these fail, and fix it. Please add a bit of description above.