I know of companies that pay salaries to full-time community managers. If you can't justify dedicating a person to it full-time, or don't have the expertise in house, why not contract it out?
* Not necessarily true, who filters for the filterers?
I agree that this is the worst startup idea ever.
On that note I'm surprised nobody's using the YouTube API to do some Akismet-like auto-filtering already.
[For StupidFilter, w]e've gathered a fairly large (225K+ comments) database of comments, primarily from Youtube, that ever-inspiring font of stupidity. We've implemented a web-based comment ranking system to seed our stupidity corpus and that's proceeding nicely.
Apparently it's now in beta...
This must be the saddest AI ever, though. Or at least the most pessimistic about humanity, being trained on YouTube comments...
Keep the most hateful stuff out, provide useful / insightful criticism and commentary.