The majority of viewed content is less than 15 minutes long, so although some 1-hour or longer videos may be good to have for some viewers who want it, it is likely to be a smaller audience who would view this.
Shorter clips would mean more videos, which means more overall content on your page and more appearances on search results, which would improve the chances of Revealers seeing your profile and content.
Returning visitors, Fans and Revealers are interested in viewing new content regularly. It is much easier to upload shorter videos regularly than it is to upload longer videos.