I've done high def, narrated walk through videos for ALL of my listings for about 3 years. It's the best listing tool out there (I get 99% of all listings that I go for)... buyers love them. Sellers love them. It weeds out the looky loos and creates a VERY serious buyer if they actually make an appointment to personally view the home.
Understand that the FIRST thing people do is whittle down the choices by doing a search on bedrooms, baths, price, location, etc. The SECOND thing they do is read the description and quickly look at the photos. The LAST thing they do is watch the video. That's the FINAL qualifier. If they get to that point, they WILL wait a minute or two for the video to load, and they WILL watch it from beginning to end.... sometimes several times, looking at EVERY nook and cranny. I've even had some people tell me they've watched videos a hundred times, talking themselves into buying the home in the meantime....!