What makes a marketing video successful? Most of the big factors have little to do with the technology, and instead are editorial and promotional in nature: The script, production, talent, and promotion/distribution.
My focus here is on a more mundane issue: where to host the video. That is, where does the video file "live". A video can be embedded into your website, but be hosted by another company like YouTube or Vimeo. (Nearly all of your customers won't notice the difference, and those that do won't care.)