It usually takes about 20 minutes for the videos to get copied from our MC service (where they are initially recorded) to the iOS service to be viewable on the iPad or iPhone. That said, if you have the MC presentation open on the device during that time (even running in the background), it won't actually refresh the presentation to show the video added (file in use). Here's what I would recommend:
Close out of the MC application entirely (double tap the circle button, then press and hold the MC icon until you get an X, then hit the X).
Wait for about 20 minutes, then try clicking on the MC link (or manually enter it in the app) and the video should appear.