If you’re looking for “after action review” type functionality, then look into the networking support. If you’ve built your game as networked, then you can record simply the network packets, which is much less than the full data, and then play them back to repeat the action.
If you want a full screen recording, look into using an NVIDIA graphics card, and the GeForce Exprerience Shadow Play feature. You press a key, and it starts recording a full screen MP4 at full resolution and high frame rate, with zero overhead. As long as you have enough free space on the disk, you can keep recording. Press another key when you’re done, and the MP4 is available in your Videos folder. Works a treat!
It has no overhead, because the NVIDIA graphics cards have built-in video encoding hardware, which can read the screen data straight from the framebuffer, when triggered through the GeForce Experience tool. (And certain specially constructed other software.)