The block that catches the people about to leave
Nobody reads a webinar page in order. They read the title, check the time, look at who is speaking, and then hunt for the thing that stops them committing an evening. That hunt usually ends at the form, and for a meaningful number of people it ends there without a registration because one small question went unanswered: how long, what do I need to have in front of me, is it going to be put online without my knowing.
An answers block is the cheapest fix available, because it works on objections you already know about. The proof is in your own inbox: every question that has arrived by email since your last session is a line a stranger will wonder about tonight. Write those down in the words people use, answer each in two or three honest sentences, and place them where the hesitation happens.