It would be nice to have the translation of the joke before going on and on about possible explanations.

Here is the joke for anyone wondering:

https://en.wikipedia.org/wiki/Bar_joke#First_recorded_example

A dog entered into a tavern and said, 'I cannot see anything. I shall open this'

Tl;dr of the video: ::: spoiler spoiler the bar is so lame that the dog plans to open his own bar :::

A man with both eyes squeezed shut walks into a bar. He cracks one open.