No better than doing it by hand

This plugin doesn’t update the ALT fields of the images from the alt tags, so, basically, it’s exactly the same as just bulk downloading the images from a remote site and bulk uploading them to your library. It does stick the local copies in the same places you had hotlinked them in your post, which is great (and is the reason I’m giving 2 stars instead of 1), unless, like me, it leaves you with 500 media files that you now need to update the alt fields individually by hand, making the whole exercise a waste of time.