Install Webcam driver: 

UVC webcam

Non UVC Camera

Install mjpg-streamer:

opkg update
opkg install mjpg-streamer
nano /etc/config/mjpg-streamer
config mjpg-streamer core	
option enabled		"1"	
option device		"/dev/video0"	
option resolution	"640x480"	
option fps		"30"	
option www		"/www/webcam"	
option port		"8080"
/etc/init.d/mjpg-streamer enable
/etc/init.d/mjpg-streamer restart

access video via browser from http://arduino.local:8080