You probably tried the static ones, it didn't work, so you also put the shared ones in there too (and then it did work). Plus, the static zip archive does not contain DLLs. You not only put the static files in there. Or later what if he looks in that folder and says 'what are all these?'

What if he's using a more recent version of something and the file overwrites it, for instance. It's a bad idea to be passing around files which may not be useful and/or conflict with someone's setup. You are correct that I have a few other plugins in there that are not related to video functionality but they don't hurt either Reaper cannot find other ffmpeg files to use those instead. I simply extracted the contents of the static version into the UserPlugins folder of my portable Reaper install to use it portably and it works for whatever reason. As I said, I don't have any shared version of ffmpeg anywhere on my machine. Let him get the correct files from the correct place. Plus you also have some of the STATIC files in there. NO! You have other files in there which are not a good idea to share, just in case he has a different configuration.

Some of those files in your folder are also from ReaPack etc., so you don't want to delete them all. If you want to know what files are needed, look in the SHARED version's 'bin' folder and then only look at the DLL files. I'm not just saying this, I actually mean it lol. Only the DLL files which are in the 'bin' folder of the SHARED version are needed for FFMPEG. The fact you put files from the shared package in that folder doesn't change anything those files aren't being used.

How to install ffmpeg to windows 10