Vid Bingo

I find instrumentals fun to work with because you're not pinned down as much by the lyrics, so you get chances to do more dynamic and interesting things with the visuals with less constraint. I've done a few vids to purely instrumental songs and I find it really satisfying. But yes, it can be tricky to figure out at first. The only answer is practice. :P

I did a panel on vidding to jazz, mostly instrumentals, at VVC last year and I think my basic advice that came out of that for dealing with instrumental passages is to first understand the music theory as much as possible. What time signature is it in, what rhythms does it use, what is the overall musical structure, what harmonic structures are used, etc... Just as much as music with lyrics has narrative that you can use, instrumental music has narrative and music theory is the language that has been developed to talk about that narrative structure. I like to put markers on my timeline at key moments: with lyrics, I mark key lyrics that I want to make sure I hit properly... with music, I mark changes in the music, changes in rhythm or instrumentation or key signature.