I personally, will never use an unknown source such as a file hosting site and there is no need to do this with plex as all the old versions are hosted by plex HERE.
Side load however you wish. However, I always recommend staying as close to the source as possible when downloading/installing software (even on android). Use the play-store for best practice and avoiding security vulnerabilities. If you are going to roll back, go as close to the source as possible.
