Webhook as return URL?

Damon,

We did something similar in order to to post Marketo data to a client's instance of On24, but make it look like our own registration.

We created two landing pages--one a reg page containing a unique form, the other a normal post-reg landing page.  We programmed the form element on the reg page to take the user to the post-reg page, just as you would with any normal form on a marketo landing page.  Its not technically the returnURL, but it contains the same information, and is mostly transparent to the user.

To get the data from Marketo to On24, we created a Smart Campaign, triggered off "fills out form"   In addition to all the stuff we wanted to do--add ot list, change lead score, remove from invitation flow, etc., we included a "Call Webhook" flow step.

The webhook was configured for the ON24 HTTP Post formatted URL, containing the ON24 event id, key, and other parameters with values set to Marketo tokens.  It looks like this:

http://event.on24.com/utilApp/r?eventid=XXXXXX&sessionid=1&key=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX&job_title={{lead.Salutation}}&firstname={{lead.First Name}}&lastname={{lead.Last Name}}&job_function={{lead.Job Title}}&company={{company.Company Name}}&address_street1={{lead.Address}}&address_street2={{lead.Address 2}}&city={{lead.City}}&state={{lead.State}}&zip={{lead.Postal Code}}&country={{lead.Country}}&work_phone={{lead.Phone Number}}&email={{lead.Email Address}}

Customer sees our Landing page & registration form, our post registration page.  They received the confirmaion email from On24, as well as any reminder messages from ON24.

The only caveat is that If the customer does not have a previous ON24 cookie, they may have to re-enter their email address on the ON24 event page on the day of the event.  Otherwise, it seems to work.