I do plan to monetize with a pro monthly subscription by adding premium features and keeping the app free for the current feature set. The email capture serves as a way for me to get feedback - not to spam you. Otherwise it's hard to engage with users.

suggestion is to have a small link to a "pro version" coming soon or something so people know that there is a reason for asking for the email/more trust in the product

For an opensource screen recorder, try https://github.com/alyssaxuu/screenity