You are testing your UAT instance after migration from Media Manager (previously called Media Console/Twistage) to the AWS video provider and you notice that your uploaded videos are not playable while the embedded videos work fine. At the same time, you may also notice some additional uploaded videos that were not present in your Jive community and seem to be playing without any issues.
This is expected behavior during UAT testing for Media Manager to AWS videos. The video data on the UAT instance is refreshed as a copy of the production data. This process copies the list of videos along with their posts but not the actual video files. Since UAT and production are different Jive instances, the copy of the video data on UAT doesn't have any file to play. This is also the reason why embedded videos continue to work fine as they are stored on an external service.
However, for testing the video functionality properly, Jive's internal teams upload a few videos as tests on the UAT instance. You may notice these videos as additional videos that are not present in your production instance but seem to be playing as expected.