Yes, the video was awful. No one can really be sure how painful certain methods of execution are. I think that the electrocution though, might be a bit quicker than the hanging. An elephant has a pretty large body - so being suspended in the air by its head cannot be comfortable at all. And sometimes one does not die immediately in a hanging. Certainly, hangings can go awfully wrong. You should read about this guy, Phil Hanna.

When Hanna was only twenty-two years old, he witnessed his first hanging, that of Fred Beheme at McCleansburg, Illinois, in 1896. The officials who conducted this execution were so inexperienced that the hanging became an accidental exercise in brutality. Deeply troubled by what he had seen, Hanna was moved to learn more about the proper manner to conduct a hanging. He read various materials and studied the subject until he became an expert. He began to officiate at hangings, directing the authorities how to proceed. Although Hanna never requested to officiate at any hanging, he was widely known for his skills, and local sheriffs and other officials across the country often requested his assistance prior to an execution.

Further down:

Hanna followed a certain protocol with the prisoner. When he arrived at the site of an execution, he visited the condemned person and announced, "I am here to help you." Hanna told people that he hoped to spare the individual some misery. He sometimes counseled the prisoners, assuring them their death would be painless. He went to great lengths to see that the subject's last request was fulfilled.

Executions should be enacted in a humane way like Hanna tried his best to ensure. There should be people that make sure it is done right if hanging is the method used. I don't think that could be very easy with an elephant. And if you were to poison him by injection or something else, it would take a very large dosage. The article said that she was given carrots with 460 grams KCN (that's about one pound) and she died in seconds. A quick death would be better than a slow one. The potassium cyanide though would be awful (I do not know why this was necessary). I do not know what the best method of death is but I think electrocution might be a better one than hanging.

Here is a list of methods of capital punishment. I personally prefer none of them for me or anyone else. I am against capital punishment for humans or animals.