Continuing the discussion from An Epic Comeback against a Tbag!:
Seeing as I’ve seen this question asked a few times, I thought it was worthwhile to have a place to share tips, suggestions, and external device recommendations for recording clips and making videos on the Xbox One. I will update this FAQ/Guide later on with screenshots/videos, as well.
There are multiple methods you can use to record gameplay on your Xbox One, and I have been doing so for a while now. I always longed to start a Youtube channel as a fun way of archiving game play, and the Xbox One has some pretty decent built-in recording and editing functions, which I am taking advantage of.
RECORDING LIVE GAMEPLAY
During gameplay (or after a Killer Instinct match has completed), use the Guide Button or your Kinect to snap the “Game DVR” app, and choose “End Recording Now,” then select the previous amount of time to wish to capture. This should create a clip between 30 seconds and 5 minutes in your Game DVR list.
RECORDING A KILLER INSTINCT REPLAY
Navigate to “Fight Archive” and then "Replays and find your chosen replay in the list. Watch this replay all the way through; you can choose to turn on the Display Inputs and Display Hitboxes on if you want those displayed on your clip. When your clip has ended, use the Guide Button or your Kinect to snap the “Game DVR” app, and choose “End Recording Now,” then select the previous amount of time to wish to capture. This should create a clip between 30 seconds and 5 minutes in your Game DVR list.
Alternatively, you can snap Game DVR before watching the replay and choose “Start Recording Now.” Then return to KI and watch your Replay as above, returning to Game DVR afterwards and choosing to end the recording.
Once you have a clip recorded using one of the methods above you can upload it directly to Youtube using the Youtube app on the Xbox One, or edit the clip in Upload Studio and share it to your OneDrive, where you can download it on your PC (to upload it you YT or elsewhere) or create a share link to share it with people.
ADDITIONAL RECORDING OPTIONS
If you have a powerful enough PC, you may also decide to record your clips through use of a device called a “capture card.” This can be an external device which connects directly to your console, or one which is internally installed in your computer. I do not have experience with this directly, and do not have a recommendation on specific devices to use; I do know that (prior to the launch of the PC version of Killer Instinct, at least) Maximilian Dood has used a capture card to both record and stream his Killer Instinct play.
Another option is to stream your gameplay live from your Xbox One (through a service like Twitch) and set the session to be “archived” where you can review it at a later date for a limited time. I believe streamed content is likely to be at a lower quality than the original broadcast.
I have heard various rumors or stances on the best/easiest ways to capture your gameplay from the PC version of Killer Instinct, but as I do not have Windows 10 I have no personal experience with KI on PC (although my machine would run it just fine), but hopefully the comments below will contain some helpful tips or suggestions.