Yep, definitely an explosion. You could see large pieces of debris blow back through the exhaust.
Redundancy! The design was so robust that issues such as a blown engine wouldn’t have been enough to scrub the mission. The design was so robust that an exploded engine didn’t take out the whole vehicle like cascading dominoes. Lets curb the criticisms just because one of the backers was a Obamamite turd!. The vehicle functioned as designed!(now lets see if the return vehicle functions).