Ive been trying to gauge what the standard length is for thse movie clips the surfer can see before joining a site and, quite frankly, im not havng much luck LOL

Some tours seem to have 15 second clips, some seem to have 30 seconds and others have 1 minute plus on their tours.

In your folks opinions, what should the ideal length of a preview movie clip be on a reality style tour?

Regards,

Lee