Assalaamu alaikum,
It is a nice story. Though for some reason, the video kept freezing.
I remember reading about some battles around the time of the Battle of Yarmuk (as I recall, in this book:
http://www.ospreypublishing.com/stor..._9781855324145). At one point, the Muslims had to abandon a town they had taken. So they returned the monies the local people had paid them, before leaving.
(smile) I suspect that this is one reason the Muslims won so easily: they were more
just than the local rulers (in this case, the Romans).
May Allah, the Preserver, Help us to remember to live our Islam.