The easiest way is to override the entry with PureSight's allow list. It will take a bit of time, as you'll have to see the URL for each MP3 and add that in the allow list, but that should resolve it for you.
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From the PureSight helpfile:
As with most non-manual systems however, there is a possibility for false positives - or even pages which cannot be categorised. This particularly applies to Flash-based websites. Because of this, PureSight has an Allow List and a Ban List, where you can specify partial phrases that are matched in the URL.
For example, if you add:
nzherald
to the Allow List, then all URLs which contains the word "nzherald" will always be allowed through i.e.
www.somegambling.org/nzherald/gamblinginnz.html
www.nzherald.co.nz
and so on. The sequence for evaluation is:
(a) Allow List
(b) Ban List
(c) Artificial Content Recognition
This means that where there are conflicts, the content in the Allow List overrides the content in the Ban List and the ACR, and the content in the Ban List also overrides the content in the ACR.