Question Author
Have been to both those sites, thanks. The first doesn't seem to say how to view at all. The second apparently needs a couple of billion 'switches' clicked because it utterly fails to realise that there is no legitimate interest in spying on someone.
(I had tried AR Viewer (Augmented Reality) app, but got no further than the camera demand.)
I think I gave up last time when it just closed after switching them all, but it seems to have remained open this time. Problem is, the file is in WhatsApp, not downloaded as such, so I'll have to work out how to extract it in order to upload it. Cheers.