I believe it can help promote events, enhance the on-site experience, and extend learning beyond the conference room or exhibition hall into the wider community, all of which helps promote your event.
Through an excellent guest post on the excellent site Conference basics (and @gchicco) by Gabriel Shalom, founder of the KS12 Creative Studio I just had an insight into what that future might look like. You can read all about here: http://www.videosprint.net/ (including some great examples) or better still visit this post on Conference Basics and here Gabriel tell you about his business model.
The most interesting aspects of Gabriels model is the image above (I also liked how there wasn’t any shots of a speaker podium or power points, or people entering and leaving the conference hall but I digress). Gabriel outlines how video can help extend the conversation, the sharing, the learning and the networking both at the event, into the hallways, the online back channels, and after the event into the wider business community by leveraging social media. The future of conference marketing involves video, but like all tools, it will be how you wield it that will make the difference.