NFHS Football Rule 1612 covers Coaches’ Field Equipment, including communication equipment like iPads and other devices that can play video clips. In the 2014 NFHS Football Rules Book, Rule 1.6.1.2 says
“Communication devices including but not limited to audio recorder, Local Area Network (LAN) phones and/or headsets, mobile phones, still photograph(s), film, analog or digital video(s) and/or Internet depictions may be used by coaches and nonplayers.”