file.pizza if this is a one off or rare occurrence. If you're doing this regularly, there are better options, provided the person at the "source" computer is competent. A significant question is whether or not these computers are on the same network. I would recommend running a HTTP server if you don't care about privacy, HTTPS if you do. There's no need to buy an SSL certificate, self-signed is more than adequate for this purpose.
It's more complicated to set up, but the advantage is that when you're done you can send the receiving party a link they can open in any web browser, no hassle.
Sm64ex-coop is amazing! I never got far in super mario 64, the camera gave me headaches. I did know it was a revolutionary game for it's time though.
With sm64ex-coop, you can enable free look with the camera, and if you set it up right it feels just like the camera in many modern games. There are hi-res texture packs (Render96) available that also look amazing. And finally, they added a bunch of mods and features, one major one being the ability to play multiplayer.
Oh yeah, and it's cross-platform, runs on a whole bunch of different devices. I highly recommend checking it out, it's sooo much better than anything you'll get from an emulator.