Hi,
This widget unfortunately is not in the AppStore yet, but is working fine according to tests. The problem is just with videos hosted by Mendix Server. If you want to use it please host your files over AWS S3 or some other Server that supports Resumeable Downloads/Streams.
Technical reason:
Safari does a check in the file URL with a Byte-range request that is not supported by Mendix Server now.
Thank you for your answer!