75 hours??? I won't probably trust anything like that to screen recorders. They may work though. But I would recommend a program that can split video say every hour. And I would test the program multiple times on several computers.

A better way is probably to use a hardware solution, the one that offers hardware encoding. If you have one computer with HDMI out and a desktop with a PCIe slot, you may use Hauppage Colossus HD PVR for recording from HDMI. You can also set up a broadcast to Justin TV or a similar service and download/capture the streaming video from it as well. Make sure to test your solution as well.