With programs like Plex that expect a filesystem and don’t natively support object storage, you will get much better performance with block storage as it’s basically a virtual disk attached to your Droplet. Object storage isn’t really meant to be used as a traditional filesystem. Mounting an object storage bucket as a directory is usually slow overall (regardless of the service providing it) compared to a regular filesystem, so there’s a possibility that it wouldn’t be suitable for streaming videos.

Another very important thing to consider is bandwidth cost. If you’re streaming videos directly out of a Space without any kind of caching you will quickly use up a huge amount of bandwidth.

You can definitely try it out, see how it goes, and evaluate!