IIRC, the main use Firewire had for PC users was to connect your DV camcorder to your computer, in order to transfer your videos for editing.
In case you don't remember (or never knew), DV was a compact video tape format that was SD resolution, but digital. It used an intraframe JPEG-like compression format, which made it popular for editing (i.e. because intraframe compression meant you could do frame-accurate edits with no recompression). DV was eventually extended to a Pro variant that had better chroma resolution and a hi-def version, IIRC. The camcorders seemed to standardize on IEEE 1394 connectivity.
For anyone with some DV tapes kicking around, continued support for IEEE 1394 means you just need to find a working camcorder to transfer them to your PC. Of course, there are hazards involved in playing old tapes, depending on how they were stored. If they were exposed to high humidity, then your best chances are with a media restoration professional.