Here in NYC open house are the best and sometimes the only way to see a home as many of the listing agents are too busy to schedule showings or want to get both sides of the deal... I try to attend as many open house as possible, so that I am familiar with what is available and then I will either schedule a showing or bring my buyers to the next open house.. Of couse video tours can be like an open house, but as a listor I want to encourage activity, as human nature makes people desire, what other people want...
Open houses work. We are heavily into marketing on the internet. Many of our internet buyers are searching online by themselves. As soon as they see a home they like, they get into the car and drive by. Then you get the call. More and more buyers will be looking for advertised open houses online. I would suggest sending emails notifying buyers that there is an open house. We send over 6000 emails to our buyers looking in our city for a home. This boosts our open house attendance.
Open Houses have several advantages even if they don't sell the home. They generate activity around the house, which reminds neighbors that the home is for sale. Sometimes neighbors are a good source of referrals, but it doesn't hurt to remind them. Open houses bring buyers to the house, which means the house could sell (and agents can sometimes turn these buyers into new clients) and open houses provide an unfiltered source of feedback about the house. I like this as a source of raw data because you never know if the feedback you get through other agents is really from the client or from the agent him/herself. In fact, during my most recent open house, I noticed an important difference between what I had been hearing from agents and what I heard from the real buyers who showed up at my open house. I'll tweak my marketing as a result.
We actually sold our old home to someone who came to see it during an open house. It was a lady who had a friend who lived on our street. We actually had lots of people (~20 each time) come by our open houses since we lived in a walking neighborhood. Our realtor also advertised heavily in the local paper and there were a few weekends that we had a color add on the front page of the Homes section! as well as the online MLS system. Lots of neighbors came by to see, but my realtor pointed out that neighbors will tell their friends who are looking to buy if they see something nice. Even though everyone has the same floor plan, some neighbors who saw us after going to our open house and commented how nicely we had remodeled our home.