How to play Apple ProRes 422 outside of QuickTime?
I know that this is an OLD question, but I thought I would add to the answers posted back in 2011.

When it was released you could not open video encoded with ProRes in video players that did not support the Apple QuickTime playback architecture since ProRes was a proprietary Apple encoding format. But in late 2011 an open source decoder became available for ffmpeg as a compile in option.

Just to be clear, ProRes was never intended as a playback format. ProRes was designed as an intermediate codec for use during video recording and editing, and was a replacement for Apple Intermediate Codec. As a result, it was never intended to be used as a "playback" format. That's why you could only play it back with QuickTime or editing software.

For optimal high quality video playback across a variety of video players (that have the horsepower to play back your video) you need to encode your video as a H.264 MPEG-4 video. You will want to set both the temporal and spacial compression to minimum, and make sure that the playback bit rate is not capped in the compression software. H.264 and MPEG-4 were designed for playback, and that's why it's the main format behind YouTube, Blu-ray, and virtual all playback systems in use today. While H.265 is starting to become more common, it is not yet as widely playable across a variety of devise.

If you do want to try and use ProRes as a playback format, then you need to make sure that the player you are using connects to the QuickTime playback codecs, and that you have the ProRes decoder installed on your system. The only video player that I know that will handle ProRes (other than pro editing systems) is VLC, and you need to have the ProRes decoder installed to make this work.