There is also a possibility to use DataMiner server as a proxy, according to the documentation: Linking a shape to a video thumbnail | DataMiner Docs

Quote from Docs:

If a client does not have direct access to the video server, it can request a video feed via the DataMiner Agent acting as a proxy server.
When a video feed is requested via proxy, the list of allowed URLs will be restricted for security reasons.

In this case, the client only needs to have access to the DataMiner Agent, and the Agent needs to be able to reach the Thumbnails server.