Our main dive attraction on Vis was a massive friendly conger that we would feed, not the one on the video. They are very confident and approach slowly, if they do bite it feels like you have been hit by a blunt object. The big ones were really smart, they would remember divemasters and follow them around even when there was no food.
The small ones are a different thing entirely, they are not as confident so they try to get in and out fast, which leads to them accidentally grabbing whatever and doing a roll to rip it off.
Morrey eels are entirely different and I refuse to feed them at all. There was a massive one on the wreck and if it came out of the hole I would get my whole group well off the bottom and move away. The ones we have in the Adriatic don't feed like congers, they shoot out fast and grab whatever looks edible to them and it's simply stupid to feed them.