Error code 43 and missing videos, please help!

Long story short,

I have an external HD hooked up to my older Mac Pro Duo Core Intel from around 2007. I put a LOT of important video clips on this external HD for edit. All was well, until the internal HD died, with a previous OS, which I believe was Mountain Lion (or the last compatible OS for my comp). Once I got my comp up and running again (this time with Snow Leopard), I checked on the external, and found that about half my videos are now an "alias" file with zero kb, and produce an error code 43 whenever I click them! Here's the thing, the one thing that ALL the alias files have in common, is that the titles have a / in them. The rest of the videos that do not, still exist on there.

When I first got the external, I formatted it with Mac drivers, before I put the videos on there. But since the internal HD crashed, the external now says "windows nt file system", and it won't allow me to store new videos onto it! Here's my question, can I still somehow recover the alias/error code 43 videos? The importance of being able to do so, is MASSIVE! This would be a huge loss if not. I spent the last 15 years getting these videos together for edit.

Please, please help!

Thank you.