mjpg-streamer on arch with uvc webcam

[youri@nemesis ~]$ pak -S mjpg-streamer-uvc

[youri@nemesis ~]$ mjpg_streamer
MJPG Streamer Version.: 2.0
 i: Using V4L2 device.: /dev/video0
 i: Desired Resolution: 640 x 480
 i: Frames Per Second.: 5
 i: Format............: MJPEG
Unable to set format: Invalid argument
 Init v4L2 failed !! exit fatal
 i: init_VideoIn failed

[youri@nemesis ~]$ mjpg_streamer -i "input_uvc.so -d /dev/video -y" -o "output_http.so"
MJPG Streamer Version.: 2.0
 i: Using V4L2 device.: /dev/video
 i: Desired Resolution: 640 x 480
 i: Frames Per Second.: 5
 i: Format............: YUV
 i: JPEG Quality......: 80
 o: www-folder-path...: disabled
 o: HTTP TCP port.....: 8080
 o: username:password.: disabled
 o: commands..........: enabled

501: Not Implemented!
no www-folder configured

http://localhost:8080/?action=stream works