Can Retroarch play movie files (recorded buttons)?

Not talking about video files but recorded emulated sessions.

If not, are there any plans in the future?

I know there are other emulators for this job but i would like to watch these real time sessions with RetroArch’s shaders.

nevertheless, you can do it, and it works on some cores. They’re called ‘bsv’ recordings, and they contain a savestate followed by a button log.