I have just bought a Canon EOS Rebel T5/1200D (not the T5i) and wanted to use it for videos at church. I had two problems the AF popping into the video and the 29 minute 59 second timer turning the camera off in the middle of the service.
I found two ways to turn off the autofocus.
1) mount the camera upside down on the tripod and it did not recognize the mouth/eyes configuration in the human face and so the AF did not come into the picture although it was not truly disabled
2) I downloaded Magic Lantern and updated the firmware in the camera. This solved two problems -- now the camera did recognize the Manual Focus/Auto Focus switch on the lens and the AF did turn off when I switched the lens into MF mode. AND ... the Magic Lantern menu let me disable that pesky 29 minute 59 second built in timer that would chop our worship and sermon recording into two pieces every time.
Now I have a GREAT webcam of the finest quality at a bargin price with all the features of a great camera for taking photos of events to be posted on our Website. This turned into a WIN WIN for me. Hope it helps others.