Can iTunes be made to play Apple ProRes files?
On 24 of July I tried for some hours to get iTunes 12.x (actual version at this time) to play other 3rd Party Codecs. In short: I was not successful. iTunes has changed a lot, so none of the older hacks work anymore.

I'm very interested in a solution for this problem, because I have a lot of FLAC-Files I would love to manage in iTunes. If I find a solution I will update this answer and provide a "Tutorial".