There are two scenarios where a video is unable to go fullscreen:
Some site builders, such as Wix, explicitly do not allow embedded iFrames to take over the fullscreen. If you are experiencing these issues, we suggest you contact the company to ask about allowing fullscreen on iFrame embeds. Feel free to loop us in (firstname.lastname@example.org) so we can provide technical details if needed!
Apple does not allow the browser to take over the fullscreen on iOS devices. Normally, Apple 'takes over' and plays videos through the native iOS player to provide a unified experience across many websites and applications. However, this native player does not support any of the interactivity that MIndstamp provides and therefore cannot be used. We understand that this is frustrating and greatly look forward to a resolution from Apple in due time.