Spot on advice. I’d observe that media files tend to be quite large, and if all that the disk has been used for has been copying these files onto it, then they’re likely to be both relatively defragmented and at the start of the disk, so the reduction in partition size isn’t going to be as slow as it usually is. (Which is very slow.)
Since media files are relatively infrequently read, I’d probably want to use a filesystem that checks against bit rot instead of ext4 - make sure that they’ve not become corrupt when you want to use them. But that’s Linux holy war territory, so I’ll leave it alone.