[unknown] Hi again, sorry for the long wait for reply.
I've updated the app and tried the video, but it still gives the same error message about unsupported format. I also retried downloading the video on my PC and then putting it on my phone's internal storage, and tried playing this local file on my phone with the SLR app's local video player, as well as DeoVR and a couple of other free VR video players on the Play Store. All failed unfortunately, and I see know way how I can actually get this video working. Yesterday I even tried purchasing another video to see whether it work (e.g. suspecting there may have been a problem with the first one) - but this gives the same error message as the original video I purchased...
In regards to Google VR Services - yes, I have that installed and updated to the most up-to-date version, as well as the Google Cardboard app and Google Cardboard Engine. All the free videos on the SLR app have always worked, but streaming or downloading any paid video and attempting to play locally just doesn't work - returning the same error message over and over.
I'm sorry I haven't found a way to resolve the issue, and I can provide evidence that these (now 2) paid videos don't work at all on my device if this is required. But at the moment, until in the future this issue may be able to be fixed, if you would be able to refund the original video and the other video I bought to test yesterday, this would be very helpful. Many thanks.