Source: LeMotif
Need a general missions explainer video? Communication consulting group LeMotif made a couple of them and can work with you on customized versions for free; pay only to license the music.
Video 1: God Has a Mission (2 minutes)
Video 2: What Is a Missionary? (2.5 minutes)
For more mission explainer videos, see this collection from Pioneers and a helpful series from Global Frontier Missions.