His explanation about why subtitles don't match dubbing is not convincing. Basically he says that subtitling and dubbing are done by different teams with different goals. The dubbing crew tries to match lip movement. OK, so why not use the script that the dubbing team produced for the subtitles? Why do the translation twice?

His explanation for that: (a) sometimes what's spoken is too long to fit as subtitles on the screen, (b) what's spoken needs to be summarized, like multiple people shouting over one another on a reality show, otherwise the subtitles would be a confusing jumble of words, and (c) jokes/slang/puns can be difficult to translate.

I that agree (a) and (b) are legitimate reasons why subtitles might occasionally not match dubbing, but (c) is irrelevant. Jokes/slang/puns might be difficult or impossible to translate, but whatever way it ends up being translated can be spoken and written identically. In fact his goose joke is spoken and written in Portuguese as Eu estou gansado deles in the same way (timecode 3:57). I.e., the dubbing matches the subtitles. So the examples he gives do not support what he did in his own video.

Furthermore, his video (like almost all videos and TV shows) is chock full of cases where the subtitles and dubbing are different for no plausible reason related to (a), (b), or (c) above:

All examples below are when the video is set to Brazilian Portuguese audio and Brazilian Portuguese subtitles.

  Time: 0:22
  Dubbing:  E o motivo disso é que as legendas e a dublagem ...
  Subtitles:  Isso acontece porque as legendas e a dublagem ...

  Time: 0:51
  D:  as legendas e a dublagem são praticamente idênticas
  S:  as legendas e a dublagem são quase idênticas

  Time: 1:08
  D:  é sincronizar o movimento dos lábios o mais próximo possível
  S:  é sincronizar os lábios o mais próximo possível

Although I agree that reasons (a) and (b) above might be valid on rare occasions, I think the real reason that subtitles don't match dubbing is because they are done by different teams with no coordination, with different timelines and deadlines, and probably by completely different companies in different countries.

If you cared strongly about this issue, I don't see any reason why the subtitles and dubbing couldn't be 99% or 99.9% identical in any particular target language. The 1% or 0.1% case being when the dialog is much too long for the screen or when you have to summarize a bunch of people talking simultaneously.