Links to youtube/nicovideo videos in song information.
This can be user submited links if you want.
Should be quite simple. If the songs in the database has ID's on them, you can create a separate database that deals with a list of what videos are with that song.
Here's a slight example of what i mean:
ID | Song
1 | Song1.mp3
2 | Song2.mp3
3 | Song3.mp3
4 | Song4.mp3
ID | Video
1 | http://www.youtube.com/watch?v=GRug5KwKauw
1 | http://www.nicovideo.jp/watch/sm982882
2 | http://www.nicovideo.jp/watch/sm1142379
2 | http://www.youtube.com/watch?v=xPS1J2YQKWg
This should be simple enough to implement.
on the song info, the video's can be a drop down list to save space on the page visualy with a "go" button that the user would click on to go to the video. If you do decide to add in user submitted links, dont forget to add in a button that says something along the lines of "Add a video" and a button that is along the lines of "Report video to administrators".
While our community is small, bringing next to zero trouble with any out of the blue videos, I think user submitted videos should not be allowed. (My opinion is loose, and wants to regret it)
Topping this with it "being simple enough to add", you're having to store all the songs as variables and then having to provide links. With a near amount of 3200 songs, this will be extremely tedious and boring. The alternative would be to add a function to "Search YouTube with This Artist And Song Name". There would be a very simple script that would replace the artist and song name with the one that is currently playing (or selected)
Now, at this point, this sounds very familiar of something else currently working right now too (But does not satisfy what the suggestion is asking).
The "Find Lyrics // encyclopaedia " when you select a song comes to mind. Meaning, if this script talked about above would go into effect, it would probably go here.