I lucked out by just googling a converter and finding one that works. It's called
SavePorn and you can either go to the site and paste the PornHub link or you can do a URL replacement. I use it on my iPhone because I am lazy.
To download using SavePorn, just replace the 'pornhub.com' part of the URL with 'saveporn.net'
- Initial Link: https://www.pornhub.com/view_video.php?viewkey=ph639b88a2c01b0
- Remove: https://www.
pornhub.com/view_video.php?viewkey=ph639b88a2c01b0
- Resulting Link: https://www.saveporn.net/view_video.php?viewkey=ph639b88a2c01b0
It seems to max out at three concurrent downloads and there's a daily download limit that I'm not sure of (during a pretty long edging session, I got carried away and it took a while to hit the limit). Pretty standard download speeds and file sizes but it depends on the quality of the videos.
Hope this helps! Sorry if it doesn't work with some videos, I haven't experimented with videos only available to premium users.