WebMetro has been advocating video content to increase conversions for many years. Based on the simple premise that you can educate and inform a user about your USP's more easily through sound and motion than through flat media, we began to not only advocate the use of video, but actually develop and deploy it over the past 2 years. What we've learned from our efforts, and the results they have driven for our clients, is that the more integrated the video feels and the less traditional it is in terms of how it is displayed, the better your chances for success.
As an example, in early 2007, video walkovers obliterated the Internet. Major media outlets and small sites alike had actors walking right over the front of the screen, attempting to hold your hand and lead you down a path to conversion. It was cute. Attention grabbing. Engaging. Then, slowly it became distracting. I remember a trade site I visited often in early 2007. By the 3rd or 4th time, it was downright annoying! But the lesson to be learned from those efforts is that people reacted to the non-traditional display of video. It was dynamic. Different. Intriguing.
In other words, don't just slap up the trade show video. Users want something of value, but they engage more richly with something unusual, interesting and / or unique. Be cautious to provide the value though. No one wants their time wasted watching an exercise in self-promotion that neither educates or compels. To truly embrace video and see the maximum lift possible from its use, you need to not only work on the content, but the strategy for how it will be woven into the fabric of the site. The more authentic, integrated and unique the video feels, the more your engagement metrics should benefit.