What is the longest youtube video?

The longest YouTube video is titled "The Longest Video on YouTube" and was created by Jonathan Harchick. It has a total runtime of 571 hours, 1 minute, and 41 seconds.

The video is a montage of random videos, music, and photographs that were put together to create a massively long video. It was uploaded on April 12, 2018, and is essentially a compilation of various content with no overarching theme.

Due to its extreme length, the video is essentially unwatchable in its entirety, and it is more of a novelty item rather than something to be enjoyed as a traditional YouTube video.