Very nice - we also had similar challenges: we have approx 20gb of videos shared across many different courses. We are now about to offer mp3 versions of the videos as well.
We have what sounds like a similar solution to yours, (but not quite), where we have a script at /resources/ that serves files to multiple courses, while tying into moodle for security checking; we even took this so far as to create a "token" of sorts whereby we can have a mirror server for our videos (coupled with our automated backup script).
A problem we've been running into, besides sharing large amounts of data across more than one course, is simply finding the resource, managing it in one location (e.g. avoiding duplicates); the shear amount of video was getting too much and is not search friendly.
To get us by until 2.0, I've just recently developed a MrCUTE Jr. shared URL/File repository plugin, which I initially was basing MrCUTE2 (thanks MrCUTE2 team!). The MrCUTE Jr. plugin allows us to have a single file or url shared across multiple courses, while maintaining security. I've just uploaded the latest version via cvs, so it should be available late evening Aug 7th (the first version currently available for download used site files for storage, so it was too insecure, imo).
I'm falling behind on my work, but I would like feedback on this solution - hopefully this will help people until moodle 2+ is rolled out along with the needed plugins. (I haven't been following 2.0 that closely of late, but last I checked it didn't have quite what we needed yet for this type of thing - my info may be out of date though).
The mrcutejr plugin page is still not showing for guest users for some reason, (perhaps something I did/didn't do - I'm new to the moodle.org system), but you can see the moodle doc page for it here.