Do you remember what messaging app you tried to use to send that video, Mary? There may be certain limits to the lengths and sizes of the video files that you can send depending on which app you use. To give you an example, the messaging app called "kik" may only let users send 10-second videos. So in cases like that, you can either try to send a much shorter video or use another messaging app, one that doesn't place such restrictions (i.e. Viber). Try to see if that can help you fix the problem.