Howard Miller

I believe that the only documentation is the comment blocks in the various lib/xxxxxlib.php files. In the case of get_fast_modinfo it's lib/modinfo.lib

Well... what it says.

You'll need to tell us about your operating system and how PHP was installed. This is a PHP problem - you're going to have to change/update something.

I don't use AWS and know very little about it, so can't help directly.

However, what do you mean by "large video files"? Hosting video as uploaded files of any description in Moodle has never been a wonderful solution. Have you considered using a dedicated video streaming solution? The like of Kaltura springs to mind but there are a few.

Not sure what this has to do with Moodle?

You can add the dependency in your theme's version.php file (https://moodledev.io/docs/4.4/apis/commonfiles/version.php), will (at least) make sure the user is aware that they need to install this.

There's dependent and then there's dependent... if it's only "nice to have" then it may be a better idea to code around it.... code a check if the plugin has been installed or not and act accordingly.