Greasy Fork

Works OK mostly.
The link is on the numerical rating provided by IMDB, right above the Play button. Could be hard to miss.
Make sure to change the @match to https://app.plex.tv/* and allow cross origin resource requests for the domain media-imdb.com
It doesn't do anything for things don't have IMDB ratings, like things that are rated by RT or TVMD instead, just to state the obvious. Only movies in your collection which have IMDB ratings will get the link.

Perfect thanks, been looking for this for ages. So annoying that Plex doesn't do this out of the box, given it shows the imdb ratings.

Hello,

I used azizLIGHT suggested change to the script but I´m getting this error:
Uncaught TypeError: imdbRatingElement is null