I have also posted this on the Windows community forum of the same topic but it is really annoying me now so I'm hoping cross posting where ever possible on this tpic will eventually get some answers.
'I'd had my 8x for about a week when I noticed my 'other' file was 6.92GB. I've only got 2GB of apps and under 1GB of music and videos. Everything else apart from the standard OS size in negligible. I've got 4 text messages and 7 e-mails on there and I've cleared all map data.
I now only have 2.22GB free. This is totally unacceptable, 20 mins or so of 1080p filming will swallow that (as tested). I know filming 20 mins of 1080p is very rare, and I don't really need more than a 16GB phone, but I don't want to have to sync and delete this often, it's quite contrary to the whole ethos of 'mobile', and I would quite like to us the 16GB I paid for.
I swear by Windows (sometimes to my detriment), had a HD7 a week after it came out, which incidentally did not suffer from this issue with almost identical info/contacts/apps on it, and even upgraded my desktop to Win8 as I wanted enhanced compatability. Has anyone actually managed to get a clear answer from Microsoft about this yet? Do we know what the file is or how to delete any of it? I'm starting to regret not getting a nexus . . . . . '
Please also note when testing the storage with the 1080p filming, it did state it was full. So much for the dynamic cache theory . . . . .