One thing that you're NOT considering is the copyright issues related to using music in fannish vids. Typically, a song is not altered as significantly (if at all) as the visual source material when creating a fannish vid. That means that any arguement claiming fair use due to "newly created" material is significantly weakened.

Also, the RIAA is also far, far more rabidly aggressive about perceived copyright infringement than other organizations. The issues of musical copyright regarding sampling and mashups have been treated somewhat differently, but even a very small sampling segment has been ruled, in some cases, to be copyright infringement and resulted in monetary damages.

The LJ community newsletter veni_vidi_vids has a section on copyright articles related to vidding every Wednesday, and there are always at least a half dozen articles linked.

So, no, I don't think that you are accurate in your assessment about the relative risks of vids versus fiction.