I don't know if it's the 3.07 update, or the switch to MC20, but playback of any MP4 video over about 15 minutes long seems to be very unreliable, with playback completely halting at a random point past that.
So far it's happened on about four different videos, roughly 20, 30, 50, and 60 minutes into playback.
Prior to these changes, I have never experienced this.
It just seems to sit there frozen or on a black screen with the "network activity" indicator spinning in the upper-left and the buffer empty.
Stopping playback and restarting it does not seem to help, nor does restarting JRemote. (quitting it by swiping off the screen, rather than resuming)