Launch into the command line with your Android 4.4 device connected to your computer and enter the command to record your screen:
adb shell screenrecord /sdcard/demo.mp4
You can further customize the speed at which it captures video, the length of time it records (the default duration is 3-minutes) and the size of the video in terms of resolution.
Another example of a command to record a video would be:
adb shell screenrecord --bit-rate 8000000 --time-limit 30 /sdcard/kitkat.mp4
The above command would record at 8Mbps, instead of the default 4Mbps, for a duration of 30-seconds and save it to the SD Card on your device with the name of KitKat. You can find a full list of commands for screenrecord here on the Android Developer Site.
