nginx hotlink protection of mp4 files with exception of mobile devices

I currently have a hotlink protection for my mp4 file like this: location ~ \.mp4$ { valid_referers blocked [login to view URL] *.[login to view URL] [login to view URL] *.[login to view URL]; if ($invalid_referer) { return 403; } gzip off; gzip_static off; mp4; mp4_buffer_size 10M; mp4_max_buffer_size 50M; limit_rate_after 10m; limit_rate 1m; } This works fine but it's blocking access from android and iPhone devices, how can I add an exception so that it allows access from mobile devices, -You do not have to log in and do it yourself as long as you can provide a working code which I can add and test. -Very urgent no time to wait.