Webcast - Web attendees watch shared video

Hi all, 

I am planning to organize a webcast. As I am aware, the attendees can only join via the web browser.

I am also planning to share my uploaded mp4 videos. Can my web attendees watch my mp4 video via their web browser?

I have read this article: https://support.goto.com/webinar/help/share-a-video-beta-g2w090120

However, I am confused with this statement: Attendees joining via the Instant Join app and mobile apps will be able to watch videos.

Does it mean my web attendees cannot watch the mp4 video ?

Really appreciate any response.