Hi. While talking about this, I'll give you an advice.
A regular video file may get pretty big. Depending on branch amd modell, the shipping software may allow you to save video as one or several video formats and hopefully let you choose bitrate that will be a major factor to file size.
If your 20 minutes long video get a gigabyte or more, you can use the convert feature in VLC to get the file size down to an acceptable level.
Tell me If this is interresting, an I can explain more as I do this with my recordings from web cam.
Concerning your database enquiry, I cannot help much. Most often when people comes to my company to teach, they store documents in regular folders that is organized in a sensible way.
Also I advice you to take a look at windows 7 libaries. That way you can organize files independent of the file/folder structure. Haven't done this myself as I don't have the need for it, but you might find it usefull.