The first major problem we had was that every now and then, the eGreat would just die by itself. After a long time, we realized that the remote of the Mede8er was somehow affecting the eGreat so we separated the eGreat from the other players and that solved the problem.
The way we did the test was that we determined the time of the scene to be tested (there were 3 different scenes, with a variety of video challenges -- natural light, dark scenes, motion, buildings, greenery). We then decided on the sequence of the players and cued the players to all play at the same time, but with a 2 minute difference between players, and then we paused the players.
We ran the first player and then called the guys in from outside the room. The first player had a 1 minute gap before the actual start of the scene. When the scene started, we put the 4 other players on "play".
The big problem was that for whatever reason, whenever we put the Mede8er on pause, it would not start properly. After a while, we decided that the only way to include the Mede8er in the test would be to have it as the first player for all 3 scenes. Otherwise, we randomly mixed the sequence of the players. Only the Mede8er was fixed as always the first player.