Our friend from blip.tv, Mike Hudack, wrote an article with some handy guidelines at Video Vertigo:
• Aggregators should always identify the individual show, videoblog or video podcast in their index, and include a link to the appropriate site for that show. When possible, the link should be to the show’s own Web site, when that’s impossible the link should be to the show’s presence on a service provider’s Web site.
• Aggregators should always conduct video playback in the video’s original player, rather than the aggregator’s player. …
• In one way or another the aggregator should make clear that the video content they’re displaying is aggregated, and not originally uploaded to the aggregator’s Web site.