The new assets with boosters seem to be corrupted. In the first place, when I imported it did not overwrite the existing prefab, as shown in the video.
Secondly the new Enemy asset does have booster particles, but none of the scripts to make it work. To fix this add Components containing the Enemy Damage and Enemy Movement scripts. I am able to get it to work by by dragging the new Enemy GO as a second child under Enemies (along with the original), and am able to get a moving and spawning enemy. However, if I try remove the original Enemy GO the new GO only spawns once. Does anyone have any suggestions?