A low-quality download strips the preview frames. A high-quality pack includes a Media folder with .png or .jpg thumbnails. Re-link the folder in the settings.
This happens with many third-party builds. To fix it on Windows, you must edit the registry or (for a safer method) use the "ZXP Installer" by AEScripts. On Mac, you must run a terminal command to disable strict signing checks. motion bro 234 download high quality
To ensure your final render is high quality: A low-quality download strips the preview frames