I noticed that on the branding and themes the welcome message will only show up once they are actually attend the webinar is this correct? There is no way to say on the registration page the welcome message or who will be presenting it until they arrive at the webinar that day?
Another option is to create your own webinar information page on your own web server that describes the webinar. You can add photos, speaker information, handouts, links, ect. Somewhere on that page you can post a link to the actual GTW registration page.