Capturing screen snapshot

To save the screen contents to a file use:

$ su
# screencap -p /sdcard/screen.png
The file screen.png is created in the /sdcard folder

Recording screen

To record a video file with screen activity use:

$ su
# screenrecord /sdcard/screen.avi
In the end of record press ^c
The file screen.avi is created in the /sdcard folder