Do you know whether or not there really are any OO churches within a reasonable distance from where you are? I think that question really is important, as some people seem to be assuming that there is an OO parish nearby and that this family chose to convert anyway. That of course makes it an entirely different situation than if there is no OO parish within a reasonable distance.
I live in a large city with many OO churches in it, so for me this would never be an issue. I have a friend, however, who lived for a while in Alaska. Alaska has no Armenian church and, as far as I know, no OO churches of any other kind. If I am mistaken, someone tell me. The fact is, my friend was only able to commune a few times a year, when she could either fly down to Washinton State, or visit down where I am. So most Sundays she either stayed home, or visited other churches where she couldn't commune.
Now my friend was actually content to do that during the years she lived in Alaska. However, when you have a family like the Ethiopians in the video, you probably would want to have a church near you where you can commune more regularly. You don't want to restrict your communing to Sundays when you have the time and the money to load your whole family on an airplane and fly to a city with an OO church in it.
I'm not saying it was a good thing for the family in the video to leave the Ethiopian Church. However, we don't know their circumstances, or what we would do in their place. Perhaps we shouldn't be too quick to judge them.
Same with judging the Serbian priest. If the priest was actively engaging in "sheep stealing" and used his influence to grab the family away from a nearby Ethiopian parish, then that is deplorable. However, if this family really does live too far from an OO church to commune there, what else was the priest to do when approached by this family? Was he to drive them away and tell them they couldn't join his church because they were Ethiopian? I don't think that would be right. Also, was he to receive them without chrismation, even though the canons of his Church tell him he needs to chrismate them? I don't think that would be right either, as disobedience is not a good thing in either the OO or EO traditions. Also, even if the priest were to just commune them without chrismation, wouldn't that have cut them off from the Ethiopian Church, as well? Unless your Church is as liberal as mine, doesn't partaking of another Church's sacraments cut you off from your own?
Personally, I think it would be great if all EO's and OO's could just commune at each other's altars. My own Church has that attitude. However, most OO and EO Churches are not that liberal. Most EO Churches require chrismation and I think the Coptic Church requires baptism and chrismation. It would be interesting to know what the Ethiopian Church requires.
In any event, I don't think we know enough about this particular situation to pass judgement on anyone. If anything, this should motivate us to support our Church when it establishes missions in new areas.