I think it's a combination of both situations. Poop-heads are still serving the files on purpose and the unaware who've downloaded them are as well.

I just did a video search for "chrono crusade" and found a 106.7kb .wmv hosted by 2 users, not only with chat enabled, but also available to "browse host". Earlier tonight, the same search yielded 43 hosts without chat enabled.

I've been ignoring / host blocking this spam file for weeks now. In the instance that returned 2 hosts, it's obvious to me that 2 people downloaded it, not realizing it's just a P.O.S., and are unwittingly hosting it. My 43 host result was one of the spam ad crank-o-matics.

I think it's very possible that, depending on the popularity of the search terms, someone else might have downloaded a spam.wmv with the exact name as the one being returned in your search results and be unknowingly lumped in with their file on the search results. And have chat enabled.

As far as encountering and deleting, I'm sure that many people, myself included, click a couple dozen things to download and then go surfthe web or play pogo games for an hour or so before checking the resulting downloads. It's VERY possible to be serving up spam in that time period.