Each gets an icon and a quirky but memorable name, like "Purple Salamander" or "Green Rodent." Click on the other computer's icon to then pick a file and send it.

Copy Finder icons in macOS's Preview app easily. You can use the macOS Finder's Copy command to copy and paste files. But here's how to use the same command to copy file icons into Preview.

I also sent a 400MB video from my PC to my Mac, and it took 50 seconds. You can also click the gear icon in the Send tab to reveal more options to send and receive files.