Quicktime on osSierra question

I recently got a new iMac, and was hoping to run MPEG Streamclip on it. The website said I needed the Quicktime component, so I copied that and a few other QT components from my older Mac to the new Mac's Library/Quicktime folder.

Now MPEG Streamclip won't even open, and just crashes - along with Compressor.

I obviously now need to remove those library components I added, but the Mac says I can't remove them as they're part of the OS.

Help! Which components should be there by default? And how do I remove those I added?

Thanks!

can you look at the dates of the components?
are there any clues there?

do you have a time machine back-up?