How to distinguish official LEGO mini movies from non-official movies?
Hello Eran's family! How are you all doing today?

Please try these methods instead:  


The Publisher's Home Page - DON'T go directly to the search box to search the term "LEGO city mini movies", but instead just
pull up one of your official LEGO mini movies and click on the
name of the person who published the video to YouTube.  

In this case it would be "LEGO". So, clicking on the content creator's name will
lead you to that publisher's homepage and everything they've posted
to YT, such as Playlists, Videos, Community chit-chats, etc...
Now, anything not created by this publisher, again LEGO, will not be on their
homepage.
Please Show Me More -  So, right below the video publisher's name and date of publication there is a video description. 

In this description field the publisher sometimes has links, or if
its a song, the song's written lyrics. Now, if the description field
gets too long and wordy, YT will cut it off after a certain length,
and hide the rest behind the "SHOW MORE" link.

So, try the SHOW MORE link to see if there's further info to
more official content.
YouTube Restricted Mode On/Off.  You can turn this on in YouTube settings to try to filter videos with potentially mature content, but note: Filters are not 100% accurate.   


Phone App - Restricted Mode On/Off


Open YouTube app.
Tap 3 dots in the top right of screen.
Look for gray "Gear Cog" to access "settings".
In settings, look for "Restricted Mode Filtering".
Choose either "Don't Filter" or "Strict". Done.








Desktop computer - Restricted Mode On/Off:


Click 3 gray "parallel lines" next to YouTube logo to open side
menu.
Scroll down/look for gray "Gear Cog" to access "settings".
Scroll down to the very bottom of page look for "Restricted Mode".
Click on it to access more of the page.
Scroll down some more. Toggle it "on" or "off".
Click "Save".
Done.