The use of a spokesperson has been a well-documented tactic in advertising. The proper spokesperson can help with the emotional triggers of identification and establish brand credibility instantly. In the online world, the use of a video spokesperson on a website is not the same use in any way. The video spokesperson does not usually confer credibility becuase they are unknown, without recognition. They are simply used to convey information. If the script is written correctly, the video actor is more like a salesperson. Somebody that stands there day and night to present a short “elevator pitch” for the company and lead the website visitor to the next most logical step for their visit. So in any traditional sense of the word, the web actor is NOT a spokesperson, just an old-fashioned salesperson.
There are some well-established rules for sales communication. There are thousands of books about how to present a sales message, but the basic principles are not new. If you miss the point that your video spokesperson should say a sales pitch, then you are missing the point. They are not a tour guide, or a “greeter”, they are a salesperson.