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If you want to record your gameplay on PC, you'll need to use a screen capture program. One of the most popular free options is Open Broadcast Software (OBS). This program is completely free and open source, and can record as well as most commercial programs. You can download OBS Multiplatform for Windows, Mac, and Linux at obsproject.com. The installer is very basic, and you can leave all of the settings at their defaults. As long as you downloaded the program from obsproject.com, you shouldn't have to worry about adware. You can find this by clicking the "File" menu and selecting "Settings," or by clicking the "Settings" button in the main window. This will allow you to adjust your basic video settings for your recordings. There are a few options that you'll want to take a look at:  Video Bitrate - This is the quality of the video. A higher bitrate will lead to a higher-quality image but lead to a larger file. Recording Path - This is the location that recorded videos will be saved on your computer. Recording Format - By default, this will be set to "flv." You may want to select "mp4" for maximum compatibility. This will allow you to assign specific keys to starting and stopping your recording. This will allow you to start recording while in the middle of a game. You can use single keys or combinations. Try to use a key that you won't be using in the game, such as one of the Function keys or a combination of Ctrl and another key. There are several things you might want to change before starting to record:  Output (Scaled) Resolution - This is the resolution that your recorded video will be displayed in. A lower resolution will lead to a smaller file, but the quality will suffer. If you want the output to be the same as you see, set it to the same value as the Base (Canvas) Resolution. Common FPS Values - This will lock the framerate of the video to the number you set (as long as your game can perform at that framerate). YouTube now supports 60 FPS video, so you may want to change this setting. If you want to record your voice along with the gameplay, you can check and enable your microphone on this tab. You can also enable push-to-talk for your microphone so that you can record your voice when the key is held. Close the Settings menu after checking your audio settings. This will create a new Game Capture entry in the Sources list. Once you've got OBS configured, you can start playing your game. You can play any game on your computer from any source, including Steam, Origin, or games installed on their own. You won't receive any indication that recording has begun, but OBS will be recording in the background. Again, you won't receive a notification that recording has stopped. The video file will be created, and you'll be able to find it at the location you set earlier.
Download Open Broadcaster Software. Run the installer. Launch OBS and open the Settings menu. Click the "Output" tab in the Settings menu. Click the "Hotkeys" tab in the Settings menu. Create shortcuts for "Start Record" and "Stop Recording." Click the "Video" tab in the Settings menu to set your recording options. Click the "Audio" tab to set your microphone settings. Click the "+" in the "Sources" frame and select "Game Capture." Start your game. Press your recording hotkey to begin recording. Press the Stop hotkey to end your recording.