On video vertigo they have provided some ethics guidelines for aggregating video.

Why are best practices needed?There have been a series of incidents in which the work of independent videobloggers, video podcasters and other creators of video works have had their content appropriated without credit by third parties. This is usually done via RSS, a technology that has led to intense value creation on the Web by making applications like podcasting possible, but acts as a double-edged sword in that it makes “page scraping” and “splogging” easier.

Steve Watkins on the vlogging list has a bit to say on this issue.