The M-50i has roughly a 2 second video trigger...Are you setting your cameras at an angle to the intended photo field? This will give the camera more time to "wake up". I have the M-40i which is basically the same camera. I have not had any problems with video on my cameras. Also, make sure your camera has the latest firmware update?
www.moultriefeeders.com/firmware-faq Go here and see if you need an update.