You can do that easily using ADB if you have your device connected via USB.
Steps:
1- Connect your device to your PC via USB
2- Drop to command prompt: Run -> CMD
3- Go to the "Platform Tools" directory in your Android SDK directory.
4- Type: adb shell screenrecord /sdcard/myVideoCapture.mp4
5- To stop recording type CTRL + C
If you like, create a BAT file to do that.
You will find the video on the root of your SDCard.