What I've seen be incredibly effective is to gate the webinars and offer them for email addresses. At this point you can drop these prospects into a highly targeted drip campaign.
To use this most effectively you would want multiple webinars for each persona you are targeting and segment them by the stage in the funnel (education, buy ready, etc.) they're most useful for. This way, by simply watching the webinar, the prospect gives you the information you need to market to them effectively.