There could be a number of different factors as to why you're experiencing some issues with playing your downloaded effects.
Please note that most video players don't natively support viewing ProRes 4444 (with alpha channels). Because of this, you will have the best experiencing previewing these types of files inside of a compositing software such as After Effects, HitFilm, or Nuke.
Here are the two most common solutions to users that are experiencing this type of playback issue:
Option 1: Make sure you have an up-to-date version of QuickTime on your computer. You can download it for free, here.
Option 2: Make sure you are using proper compositing software that supports ProRes files (Nuke, Adobe After Effects, Hitfilm, etc).
Here are just a few of the many programs that are supported:
- The Foundry's Nuke
- Adobe After Effects
- Adobe Premiere Pro
- HitFilm and HitFilm: Express
- Apple Final Cut Pro
- Apple Final Cut Pro Motion
- AVID Media Composer
- Vegas Pro 15
- Blackmagic Design: Fusion