The correct answers to these open questions are the following.
Although the question does not provide the link or the name of the video, we can comment on the following.
The causes of the Great War were imperialistic issues, feelings of nationalism in European countries, the formation of powerful armies in the region, and a series of alliances due to political, economical, and imperialistic interests.
The most critical cause was the assassination of Archduke of Austria-Hungary Empire, Franz Ferdin and his wife Sophie, during a visit to Serbia. This was one of the main causes that detonated the beginning of World War 1. One of the things that I learned that I did not know was the motives that forced United States President Woodrow Wilson to ask Congress for a declaration of war against Germany.
