A webinar is a lead magnet - you give them value, they give you their email id. Video is great at building rapport, and much more fun than a boring PDF report.
So that's really what your webinar should be: Packed with great value, VERY little fluff, then you make an offer at the end. Doesn't HAVE to be an obnoxious sales pitch, but there absolutely needs to be a call-to-action.
Check out my Kindle book about creating an Alexa Flash Briefing: https://CutToTheChase.fm/flash/
https://CutToTheChase.fm
