How to generate video out of images via WordPress plugin

What you’re trying to do is likely to upset shared hosters regardless because generating video is not cheap from a computational resource standpoint, and most rules on a shared host are because there isn’t much in the way of resources to begin with. You would be best carting your images off to a service that would do the job for you.

Trying to duplicate the work of ffmpeg etc in PHP will likely exceed the execution timeout, so you’re not going anywhere where shared hosts are concerned. You may be able to get away with GIFs, and keep ffmpeg support for those on a VPS