Consumers love online video, but sometimes it can be a challenge to find what they are looking for. YouTube remains the most obvious choice for a video search, but users can only search content hosted by the site, and copyrighted content can be difficult to find.

Enter video search engines like VideoSurf and CastTV, which try to deliver more relevant results from a range of video-hosting sites by employing new technologies.

CastTV has undertaken the ambitious act of indexing every video on the web, making it a one-stop-shop for video search.

While users may have difficulty finding copyrighted content on YouTube, they'll have no such trouble on CastTV, which links its results directly to the publisher of a video, according to The Wall Street Journal.

VideoSurf, meanwhile, uncovers relevant videos with technology that identifies the characters within certain videos. After searching for the TV show "Lost," searchers can then click on a picture of actress Evangeline Lily and find more video clips of her appearing outside of the show.

Even YouTube's parent company, Google, is getting in on the video search act with Google Elections Video Search, which uses speech recognition to transcribe and index videos uploaded to YouTube's politician channel.